Miner for a Lode of Iridium

Ages of Rock, Rock of Ages

2012-01-14T04:25:00.000-08:00

Tracing Earth's Oldest Rocks

By Allan Fraser

How old is planet earth? Our Solar System formed from a vast cloud of gas and dust 4.65 billion years ago. The age of 4.65 billion years is well established from the decay rates of radioactive elements found in meteorites and rocks from the Moon as well an abundance of evidence from chemistry and physics. As Earth is a dynamic planet in which rocks are continuously being recycled by plate tectonics much of the primordial material from the time of the formation of the Earth is no longer around. If there are any of Earth's primordial rocks left in their original state, they have not yet been found. The oldest rocks found to-date on Earth are those of the Nuvvuagittuq greenstone belt and these give an age of 4.3 billion years. It was not until relatively recently that it has been possible to measure the age of rocks. The early ideas of the age of the Earth date to the ancient Greeks and Romans and it was not until the late 1700s that scientists begun to realise that the Earth was indeed ancient. However, it was not until the discovery of radioactivity and the invention of the mass spectrometer that the quantification of isotopes of various radiometric decay schemes could be performed. In recent decades improvements in detector technology and electronics in mass spectrometers has resulted in an improvement in the precision of analytical data translating to an increased confidence in the radiometric ages. The use of hyphenated analytical techniques such as laser ablation - mass spectrometry has also allowed the analysis of small sample sizes and individual crystals.

In the Beginning

The ancient Greeks and Romans realised that long time spans were required to lay down the thick layers of sediments observed and from this they estimated that the Earth was thousands of years old. But it wasn't until the late 1700s that scientific interest in geological age began when Scottish geologist James Hutton (1726-1797), who observed that sediments built up on landscapes were indeed indicative of an old Earth (Dalrymple, 1991). Before then, the Bible had provided the only estimate for the age of the world. Bishop James Ussher (1581 – 1656) established the time of “creation” to 6000 years. Using the book of Genesis as a history book, Ussher meticulously examined the genealogy of the Bible and concluded that the date of the creation as the night of Sunday, 23 October 4004 BC (McSween, 1997). Today some biblical scholars, as well as a number of literalist evangelical Christians, believe in a literal interpretation of the Bible calling for a 6000-year-old Earth (Barr, 1984). In 1785 Hutton published ‘Theory of the Earth’ in which he concluded that “slow” processes shape the Earth, mountains arise continuously as a balance against erosion and weathering and the physical and chemical laws that govern nature are uniform. Most geological processes are extremely slow, and evidence for slow change was everywhere; rivers eroded rock and rain inexorably wore away the tops of mountains and the slow movement of glaciers carved out entire valleys. Hutton and other contemporary scientists of the time concluded that the single most important factor why the Earth looks like the way is does was due to time, and lots of it. With this Hutton established the ‘Doctrine of Uniformitarianism: "Present is key to the past" (Ward, 1995). Hutton used fossils to establish relative ages of rocks. There was however a need to determine the absolute age of the Earth. In the late 19th Century this question was first addressed by William Thompson (Lord Kelvin, 1824 - 1907). Kelvin assumed that the Earth was originally molten and calculated a date for the age of the Earth using the then young science of thermodynamics. His calculation was based on the cooling of the Earth through conduction and radiation of heat. Kelvin’s age of Earth was calculated to be about 24-40 million years (Ward 1995). The problem with this view is that the Earth has an internal heat source from radioactive decay – a fact not known to Lord Kelvin at the time of his estimation of the Earths age. At around the same time, John Joly (1857 – 1933) calculated the rate of transfer of salt to the ocean as a means to determine the age of the Earth. The age of Earth by this method was calculated to be 90-100 million years. The main problem with this approach was there was no means to account for recycled salt, salt incorporated into clay minerals and salt deposits. Later work by other scientists used the thickness of total sedimentary record, to determine an age of 500 million years. It was not until the discovery of radioactivity by Henri Becquerel in 1896 that geologists had a tool for determining the age of rocks and ultimately the age of the Earth (Dalrymple, 1991).

Figure 1: William Thomson, (Lord Kelvin) (1824 – 1907). Kelvin assumed that the Earth was originally molten and calculated a date for the age of the Earth using the science of thermodynamics. Source: Wikipedia.org

Figure 2: James Hutton (1726-1797). A Scottish farmer and naturalist, is known as the founder of modern geology. Source: Wikipedia.org

Figure 3: Ernest Rutherford (1871-1937). A New Zealand-born British chemist and physicist who became known as the father of nuclear physics[2] In early work he discovered the concept of radioactive half-life, proved that radioactivity involved the transmutation of one chemical element to another. Source: Wikipedia.org

Nuclear Changes in Nature

The solid rock of the Earth’s lithosphere formed from molten material that cooled and hardened. And in this process a “clock” that gives the age of the rock was going. Within the molten rock there are trace amounts of uranium-238, a radioactive element. Once the rocks had cooled this element was firmly locked in the rock. The atoms of uranium-238 however, decay at a constant rate to form atoms of lead-206 which would also be sealed within the solid rock. With the passing of time the rock would have less and less atoms of uranium-238 and more atoms of lead-206. Therefore, the rock contains some of the original amount of uranium-238 and the decay product, lead-206. Since we know the rate at which uranium-238 decays to lead-206, and the amounts of each of these atoms remaining we can calculate the age of the rock (Brandwein, 1968).

In 1905, Ernst Rutherford and Bertram Boltwood used radioactive decay to measure the age of rocks and minerals. And in 1907, Boltwood suspected that lead was the stable end product of the decay of uranium. He then published the age of a sample of urananite at 1.64 billion years which was based on Uranium-Lead dating (Ward 1995). Scientists of the time began to realise that our planet was indeed ancient and may exceed 2 billion years in age and the search for older and older rocks was on. The invention of the Mass Spectrometer in 1918 allowed isotopes of different atoms to be separated and quantified including four isotopes of lead and two isotopes of uranium (McSween, 1997). Many radioactive elements can be used as geological clocks. Each element decays at its own constant rate. Once this decay rate is known, geologists can estimate the length of time over which decay has been occurring by measuring the amount of radioactive parent and the amount of stable daughter elements.

There is no doubt of the Earth’s antiquity. Abundant and conclusive evidence of this is found in the rock record. However, fragments of Earth’s early primordial crust are extremely rare as most of it has been melted and recycled numerous times by plate tectonics since the Earth formed (Dalrymple, 1991). If there are any of Earth's primordial rocks left in their original state, they have not yet been found. Meteorites formed at the same time as the rest of the material in the solar system. Therefore by dating meteorites, we also get the age of the Earth, Mars, the Sun and everything else in the solar system. The best age for the Earth is 4.54 billion years (4.54 Ga)which is based on radiometric dating of iron meteorites, specifically the Canyon Diablo meteorite (Ward 1995). The Moon is better preserved that the Earth because it has not been disturbed by plate tectonics or erosion and therefore its more ancient rocks are more abundant than Earth’s ancient rocks. Rocks returned to Earth by the Apollo missions show that the oldest moon rocks have ages between 4.4 and 4.5 Ga. This is an important data as it provides a minimum age for the formation of the Moon (Dalrymple, 1991). However, remnants of ancient rocks exceeding 3.5 billion years (3.5 Ga) in age are found on all of Earth's continents. In 2008 a research group from McGill University discovered an amphibolite in Northern Quebec in an area known as the Nuvvuagittuq greenstone belt which has been radiometrically dated to 4.3 Ga (ref 8.), making them the oldest rocks discovered so far on Earth. Before the McGill study, the oldest dated rocks were from a body of rock known as the Acasta Gneiss in the Northwest Territories of Canada, which are 4.03 billion years old (ref.8). Other rocks that have been studied are nearly as old are also found in the Minnesota River Valley and northern Michigan (3.5-3.7 Ga), in Swaziland (3.4-3.5 Ga), and in Western Australia (3.4-3.6 Ga) (Barton et al, 1978). Southern Africa also has a host of rocks dating to more than 3 Ga, such as the Sand River Gneisses in the Limpopo Valley of South Africa, have been dated at 3.79 billion years (Barton et al, 1978).

Modern Mass Spectrometry methods are used with laser technology and this has made it possible to analyse very small samples such as zircon crystals down to single grains and achieve very high accuracy and precision (Kruger et al, 2000). An improvement in the precision of analytical measurement allows a reduction in the uncertainty of measurement of an individual zircon crystal or a population of zircons from a particular rock deposit (Allen, 1999). The knowledge of the uncertainty implies increased confidence in the analytical determination and does not imply doubt about the validity of a measurement (Fraser, 2010).

Conclusion

There is abundant evidence that our planet is indeed ancient. This has made us think in terms of deep time, which has profoundly affected the way we the way we see ourselves in the world.

A small Collection of some of Earth’s oldest Rocks

Figure 4: A 5 cm specimen of gneiss from an outcrop of the Acasta gneiss in northern Canada. This gneiss outcrop is dated at 4.02 billion years which is considered to be from one of the oldest outcrop of rocks on Earth. Specimen and photograph: A. Fraser.

Figure 5: 3.6 billion year old Morton Gneiss, Minnesota, USA. 9 cm. Specimen and photograph: A. Fraser

Figure 6: 3.2 billion year old granite specimen (8 cm) from the Klein Jukskei River, Johannesburg. Specimen and photograph: A. Fraser

Figure 7: A polished section of Mary Ellen Jasper (7 cm) from Minnesota USA, dated at 2.5 billion years. Specimen and photograph: A.Fraser

Figure 8: Greenstone schist (8 cm), Walter Sisulu Botanical Gardens, JCI Trail.
Specimen and photograph: A. Fraser

Tracing Earth's Oldest Rocks

Figure 9: Barberton Greenstone (4 cm) dated at 3.3 Ga. Specimen and photograph; A.Fraser

References:

1. Allen L.A., Georgitis S.J., (1999) “Technical Brief - High Precision Isotope Ratio Measurements by the LECO Renaissance™ TOF-ICP-MS.
2. Barr. J. (1984). "Why the World Was Created in 4004 BC: Archbishop Ussher and Biblical Chronology", Bulletin of the John Rylands University Library of Manchester 67:575–608
3. Barton, J. M., Jr., B. Ryan, & R. E. P. Fripp. (1978) “The relationship between Rb-Sr and U-Th-Pb whole-rock and zircon systems in the 3790 m.y. old Sand River gneisses, Limpopo mobile belt, Southern Africa”. In R. E. Zartman, ed. Short papers of the fourth international conference, geochronology, cosmochronology, isotope geology. U.S. Geol. Survey Open-File Report 78-701. Page 476.
4. Brandwein P.F., Stollberg R., Burnett R.W., (1968), “Matter, it’s forms and changes” Harcourt, Brace & World, Inc. Page 182
5. Dalrymple G.B., (1991). “The Age of the Earth” Stanford University Press.
6. Fraser. A.W., (2010). “Statistical Method Validation in Analytical Chemistry – a practical approach”. Training course for Samancor.
7. Kruger, F.J., Allen, L., Fraser, A.W., (2000) “Combined electron probe and LA-ICP-TOF-MS analysis of Major and trace elements in garnet, apatite and zircon” Geoanalysis 2000.
8. McGill University (2008, September 26). Oldest Known Rocks On Earth Discovered: 4.28 Billion Years Old. ScienceDaily. (Accessed April 19 2011).
9. McSween. H.Y., (1997) “Fanfare for Earth – the origin of our planet and life”. Pages 160-161.
10. Ward, P., 1995 “The End of Evolution” . Phoenix Grant Science ISBN 1-85799-368-3. Page 133.

Allan Fraser is a consulting analytical chemist and a registered Professional Natural Scientist with the South African Council for Natural Scientific Professions. His area of interest is in the minerals of the Kalahari manganese field, the Phalaborwa Carbonatite and Peru. Allan’s other areas of interest are rocks of Archean and Hadean age, meteorite impacts and their relation to extinction events (the Cretaceous-Tertiary extinction event in particular) and the geology of Mars and Earth’s moon.

Allan Fraser
PO Box 369
Fourways
2055
mineralman@telkomsa.net

2012 End of the World - Another dumb-ass Prediction

2012-01-12T09:32:00.000-08:00

2012 proves to be an eventful year with the end of the world looming in December. Well, that’s if you are a proponent of some very bizarre speculation about Mayan astronomy. How could the Mayan civilisation, concerned with predicting what would happen in a future millennium not use its vast knowledge to save itself from self-destruction? The Mayan elite, high priests and prophets couldn't see far enough into the future to plan for and solve the human problems they faced which ultimately lead to the abandonment of their cities due to a revolt by the plebs. Moreover, the Mayans never predicted the Spanish Conquistadors butchering hundreds of thousands of Mayans in the sixteenth century. So, why should we think the Maya prophets would be any better at seeing the distant future than other failed prophecies? Well, I’ve said my bit on this for the year.

The Gap is closing

2012-01-04T08:37:00.000-08:00

Early humans used “Gods” and the “supernatural” to explain the sun and moon, natural disasters and disease. When we started using science to elucidate the natural world the gaps where the God's dwell started to shrink. The gaps grew smaller as science revealed how insignificant we were in the Cosmos and how it so eloquently explained the evolution of species through natural selection and allowed the development of antibiotics to cure disease. Everything we know about the Universe points to it operating by absolute physical laws of cause and effect. The Universe, however, does not look like one in which an independent outside agent is intervening, nor is it a Universe in which miracles happen and physical laws are violated by an entity that is above these laws.

Reliability of Radiometric Dating

2011-07-30T01:08:00.000-07:00

I have read several blog sites in which there is discussion on the age of the earth and inevitably the topic of the dating of rocks and the reliability of this method and it's data is questioned. Radiometric dating relies on the natural decay of radioactive isotopes. It is a reliable and accurate way to determine the ages of rocks. As with all measurement there is uncertainty in that measurement which can however be quantified. Over the last few decades the advancement in the instrumentation (mass spectrometers) has improved precision of measurement, hence reducing the uncertainty of measurement of rock age. Dates determined by one radiometric scheme can often be verified by independantly determining the age by an alternative radiometric scheme. All of this nonsense about not believing that radiometric dating is accurate stems from the proponents of a "Young Earth" and people feeling threatend by the advancement of science.

Radioactive decay is the spontaneous release of energy in the form of radioactive particles or waves. It results in a decrease over time of the original amount of the radioactive material. A quantity is said to be subject to exponentional decay if it decreases at a rate proportional to its value. Symbolically, this can be expressed as a differential equation where N is the quantity and λ is a positive number called the decay constant: ∆N = - λN/∆ t. The number of decays are represented by ∆N
The short time interval that ∆N occurs is represented by ∆t N is the number of nuclei present λ is the decay constant.

How old is planet earth? Our Solar System formed from a vast cloud of gas and dust 4.65 billion years ago. This age of 4.65 billion years is well established from the decay rates of radioactive elements found in meteorites and rocks from the Moon as well an abundance of evidence from chemistry and physics. As Earth is a dynamic planet in which rocks are continuously being recycled by plate tectonics much of the primordial material from the time of the formation of the Earth is no longer around. If there are any of Earth's primordial rocks left in their original state, they have not yet been found. The oldest rocks found to-date on Earth are those of the Nuvvuagittuq greenstone belt and these give an age of 4.3 billion years. It was not until relatively recently that it has been possible to measure the age of rocks. The early ideas of the age of the Earth date to the ancient Greeks and Romans and it was not until the late 1700s that scientists begun to realise that the Earth was indeed ancient. However, it was not until the discovery of radioactivity and the invention of the mass spectrometer that the quantification of isotopes of various radiometric decay schemes could be performed. In recent decades improvements in detector technology and electronics in mass spectrometers has resulted in an improvement in the precision of analytical data which translates to an increased confidence in the radiometric ages. The use of hyphenated analytical techniques such as laser ablation - mass spectrometry has also allowed the analysis of small sample sizes and individual crystals.

The ancient Greeks and Romans realised that long time spans were required to lay down the thick layers of sediments observed and from this they estimated that the Earth was thousands of years old. But it wasn't until the late 1700s that scientific interest in geological age began when Scottish geologist James Hutton (1726-1797), who observed that sediments built up on landscapes were indeed indicative of an old Earth. Before then, the Bible had provided the only estimate for the age of the world. Bishop James Ussher (1581 – 1656) established the time of “creation” to 6000 years. Using the book of Genesis as a history book, Ussher meticulously examined the genealogy of the Bible and concluded that the date of the creation as the night of Sunday, 23 October 4004 BC (McSween, 1997). Today some biblical scholars, as well as a number of literalist evangelical Christians, believe in a literal interpretation of the Bible calling for a 6000-year-old Earth (Barr, 1984). In 1785 Hutton published ‘Theory of the Earth’ in which he concluded that “slow” processes shape the Earth, mountains arise continuously as a balance against erosion and weathering and the physical and chemical laws that govern nature are uniform. Most geological processes are extremely slow, and evidence for slow change was everywhere; rivers eroded rock and rain inexorably wore away the tops of mountains and the slow movement of glaciers carved out entire valleys. Hutton and other contemporary scientists of the time concluded that the single most important factor why the Earth looks like the way is does was due to time, and lots of it. With this Hutton established the ‘Doctrine of Uniformitarianism: "Present is key to the past". Hutton used fossils to establish relative ages of rocks. There was however a need to determine the absolute age of the Earth. In the late 19th Century this question was first addressed by William Thompson (Lord Kelvin) (1824 - 1907). Kelvin assumed that the Earth was originally molten and calculated a date for the age of the Earth using the then young science of thermodynamics. His calculation was based on the cooling of the Earth through conduction and radiation of heat. Kelvin’s age of Earth was calculated to be about 24-40 million years (ref.). The problem with this view is that the Earth has an internal heat source from radioactive decay – a fact not known to Lord Kelvin at the time of his estimation of the Earths age. At around the same time, John Joly (1857 – 1933) calculated the rate of transfer of salt to the ocean as a means to determine the age of the Earth. The age of Earth by this method was calculated to be 90-100 million years. The main problem with this approach was there was no means to account for recycled salt, salt incorporated into clay minerals and salt deposits. Later work by other scientists used the thickness of total sedimentary record, to determine an age of 500 million years. It was not until the discovery of radioactivity by Henri Becquerel in 1896 that geologists had a tool for determining the age of rocks and ultimately the age of the Earth.

Radiometric dating is no mystery .... the truth is out there.

Human Evolution - The Evidence -

2011-06-11T00:28:00.000-07:00

There is overwhelming evidence for human evolution. All human beings and all other life forms evolved from ancestral species. The four main lines of evidence for human evolution are:
1. Our relation to living primates;
2. Vestigal organs/structures such as the appendix;
3. The fossil record;
4. Genetics;

Hypothesis Testing

2011-05-30T08:01:00.000-07:00

As a scientist and a rational human being, learn to question everything and strive to find answers on your own through research. 'Doubt' is the most sacred thing for a scientist and an adherent of the scientific method. This doubt keeps you on focused when you feel like surrendering or believing in something at face value without adequate scientific research. As scientists, we constantly strive to create a rational and lucid picture of the world by piecing together one fact at a time, through theorising and experimentation (Pilgrim, 2011). A Hypothesis means to “Ask a Question of Nature”. In Science we often need to test our hypothesis. A hypothesis is an educated guess, based on observation. Usually, a hypothesis can be supported or refuted through experimentation or more observation. A hypothesis can be disproven, but cannot be proven to be true (Helmenstine, 2010). To test the hypothesis we create an experiment that will yield one of two answers: Yes or No or True or False. The classical way to make statistical comparisons is to prepare a statement about a fact for which it is possible to calculate its probability of occurrence. This statement is the null hypothesis and its counterpart is the alternative hypothesis (Fraser, 2011). The null hypothesis is traditionally written as H0 and the alternative hypothesis as H1 or Ha. A statistical test measures the experimental strength of evidence against the null hypothesis. A Null Hypothesis is a statement that the difference between two values can be explained by random error. It is retained if the test for significance does not fail (H0). A null hypothesis assumes that the numerical quantities being compared are the same. The probability of the observed differences appearing as a result of random error is then calculated from statistical theory. The alternative hypothesis is therefore a statement that the difference between two values is too great to be explained by random error. The alternate hypothesis is accepted if a test for significance shows that the null hypothesis should be rejected (Ha or H1). Typical tests for significance are the F ratio test and the t-test. If we reject the null hypothesis at say, a 95% confidence level, there is a 5% probability that the null hypothesis was incorrectly rejected. An example of hypothesis testing is:

Let μ1 and μ2 be the means of two samples; If one wants to investigate the likelihood that their means are the same, then the null hypothesis is:
H0: μ1 =μ2
and the alternative hypothesis is:
H1: μ1 ≠μ2
but it could also be:
H1: μ1 >μ2
The first example of H1 is said to be two-sided or two-tailed because includes both μ1 >μ2 and μ1 <μ2; The second is said to be one-sided or one-tailed. The number of sides has implications on how to formulate the test (Fraser 2011).

References:

Fraser A.W., (2011), “Statistical Method Validation for Analytical Methods – a practical approach”
Helmestine A.M., (2010) “Scientific Hypothesis, Theory, Law Definitions” http://chemistry.about.com/od/chemistry101/a/lawtheory.htm (accessed 25 May 2011)
Pilgrim G. (2011) “Hypothesis versus Theory” http://www.buzzle.com/articles/hypothesis-vs-theory.html (accessed 25 May 2011)

Sue the Advertisers

2011-05-23T12:12:00.000-07:00

The world did not end, which raises the question: should we sue the advertiser that predicted the Rapture / end-of-the-world for false advertising?

Humans from Monkeys?

2011-05-02T07:09:00.000-07:00

I refer to your older article on the Waterberg and human evolution. Do you honestly believe humans come from monkeys? Johan, Pretoria Gem and Mineral Club

Hi Johan,

Well, no. We did not evolve from monkeys. Monkeys are our evolutionary cousins, so to speak. A common ancestor of all humans, apes and monkeys existed around 12 million years ago. This common ancestor gave rise to the Asian apes and the African apes. These species developed along their separate ways. About 6 million years ago, in Africa, what are known as the bipedal woodland apes – species such as the Australopithecines and our Homo Sapiens lineage evolved. Then at about 2.5 million years ago, also in Africa, the chimpanzee and the bonobo became separate lineages. I am certainly no expert on this subject and I would refer you to the literature available on the subject for more detail and accuracy that I can provide.

The Universe – Cause and Effect

2011-04-09T11:26:00.000-07:00

The Universe is an unimaginably massive and complex system. Everything we know about the Universe points to it operating by absolute physical laws of cause and effect. The Universe, however, does not look like one in which an independent outside agent is intervening, nor is it a Universe in which miracles happen and physical laws are violated by an entity that is above these laws. The application of Occam's razor deletes the hypothesis of a supernatural origin of the universe. And every attempt to demonstrate the existence of any supernatural force affecting the universe fails through rigorous scientific examination. Cosmology provides explanations for how, out of a singularity and subsequent explosive expansion 13.7 billion years ago, the universe came into being.

Rock of Ages

2011-04-03T10:29:00.001-07:00

A sample of the Acasta Gneiss. The Acasta Gneiss is dated at 4.2 billion years old. Specimen size: 5 cm. Specimen and picture: A. Fraser

It is generally accepted that the age of the Earth and the rest of the solar system is about 4.55 billion years (plus or minus about 1%). This value is derived from several different lines of evidence. Unfortunately, the age of the Earth cannot be determined directly from material that is solely from the Earth. Meteorites have been used to date the age of the Earth as these and the other planets were formed at the same time. The Earth is a dynamic planet and the processes of erosion and crustal recycling as a result of plate tectonics have destroyed the entire earliest surface of the Earth. The oldest known exposed rock outcrop found so far is that of the Acasta Gneiss in Canada. The Acasta Gneiss was dated by radiometric means at 4.2 billion years (4.2 Ga) in age (Tsuyoshi, 2007). And, I have a specimen of the Acasta gneiss!

Science Illiteracy – it’s just depressing

2011-03-13T23:35:00.000-07:00

Scientific illiteracy is depressing. It is one of the reasons that creationism, intelligent design (ID) and a plethora of pseudoscience are accepted by so many. It seems that scientific illiteracy and the mistrust of science is on the rise. The media is replete with discussions of intelligent design (IDiocy) and climate change denial ostriches. Many people nowadays cannot address even the simplest scientific question.

How many adults understand what molecules are, and how many can identify DNA as a key to heredity or that the Earth is 4.56 billion years old and not 6000 years old. The lack of a basic understanding of how the earth works is also obvious whenever large earthquakes such as the occurrence 9.0 magnitude quake in Japan last week is covered in the news. The news anchors always ask the same dumb questions of geophysicists ….. how do earthquakes occur, are they on the rise and can we predict them? I am willing to bet that there are still people that believe that the Sun revolves around the Earth! No wonder people confuse scientific research with obsolete religious dogma or far-rightwing political discussions.

Your Mineral Specimen has been Impounded!

2011-02-18T08:16:00.000-08:00

As a collector of mineral specimens I often purchase specimens over the Internet. I frequently buy from mineral dealers that specialise in minerals from Peru as I have an interest in minerals from that country. In April 2008 I ordered a mineral specimen from a dealer in Arizona who happened to have a few really neat Peruvian pieces for sale on his web site. After some negotiating of the price I purchased a specimen of aesthetic crystals of siderite, tetrahedrite, chalcopyrite and arsenopyrite. The dealer told me that he had purchased the specimen from a Peruvian dealer at the 1989 Denver Show and that the specimen was from the famous Pasto Bueno mining district. I asked the dealer to ship to specimen to me in South Africa and I further advised him to send it insured with some form of tracking number. With a tracking number one can monitor the progress of the parcel as soon as it comes into South Africa and this is done by simply logging onto the local postal services web page. Directly after my purchase I was advised by the dealer that the specimen had been shipped. I enquired as to whether the parcel had been insured and if he could give me the tracking number. After a week went by he responded to say that he could not insure the specimen and that he has no tracking number for it, but he confirmed that he had indeed mailed it to me. I was concerned with this as it made the parcel vulnerable to theft or simply getting lost in the postal system. A month later the parcel had still not arrived, but I had in the past waited for up to 3 months for a parcel to arrive from Peru so I was not too concerned at this point. I became very concerned when the parcel had not arrived at the end of June. I contacted the supplier again and he suggested that we wait a few more weeks for its arrival. He assured me that if I did not receive it he would refund me in full. Around that time I had read of the theft of mail by local postal workers and how it was on the increase. I imagined the worst - my parcel being stolen by a postal worker who had considered it worthwhile to steal due to its higher than usual weight. I further went on to imagine that the thief had opened the parcel, found what appeared to him to be a worthless rock and had thrown it by the side of a road. It seemed so tragic an event that this specimen may have ended up this way if one considers its formation, geological history and uniqueness. The various carbonate and sulphide minerals would have crystallised in a large rock cavity around 25 million years ago, precipitating from cooling hydrothermal fluids and changes in pH deep within the tectonically active Peruvian Andes. In 1989 mining activity would expose the pocket allowing the light from a Peruvian miner's headlamp to penetrate the darkness onto masses of golden glistening chalcopyrite, quartz and black lustrous sulphide minerals. The miner would have painstakingly removed as many specimens as he could before further mining activity would send them to the crusher. He knew the value of these specimens and taking care that they were not damaged during their removal would mean he could sell them for a few more dollars to supplement his meager pay. One of the specimens he removed was sold to a dealer at the Denver Show in 1989 who placed a picture of it on his mineral web site, which turned out to be the specimen I purchased.

In the middle of September I still had not received the parcel and had not been refunded by the dealer. In late September I received a letter from the customs office at OR Tambo International Airport. The letter stated that an overseas parcel of mine had been impounded as the contents contained iridium and other precious metals. I was astounded! Iridium* is one of the rarest elements on earth and customs had apparently found enough of it in the mineral specimen to impound it! I was told by customs that the parcel had been opened and since the content was not something they recognised, they contacted the South African Diamonds and Precious Metals Regulator (SADPMR) to inspect the specimen. The specimen was analysed by an inspector from SADPMR using a hand-held Energy Dispersive X-Ray Fluorescence spectrometer (EDXRF), which according to the inspector had “detected” appreciable amounts of iridium in the specimen. On that basis the SADPMR advised customs to impound the specimen and have me apply for a license to be in the possession of “unprocessed precious metals”. I was further told by the DPMR that if I disputed their findings the DPMR would have the specimen analysed at Mintek at my cost. I called the inspector at the DPMR that had done the analysis and he very proudly confirmed that he had found iridium in the mineral specimen. As an analytical chemist I have built a career on analysis of materials and I know only too well the pitfalls that accompany chemical analysis, especially where trace element analysis is concerned. I argued with him that a hand-held XRF ('ray' – guns, as I later started calling them) with which he performed the analysis would not provide enough sensitivity or optical resolution to detect iridium at low concentrations. Even detection of an element with such an apparatus does not guarantee a quantitative result. The mineral specimen would also contain large amounts of the elements, iron, copper, carbon, arsenic and other metals and these would all contribute to what analytical chemists call “matrix effects”. These matrix effects would completely mask the presence of all trace elements and give a false positive result for iridium. The analysis of iridium in a complex matrix such as this mineral specimen would be at best a challenge even for large Wavelength Dispersive XRF instruments that have higher sensitivity and resolution and are designed for low-level elemental concentrations. With this in mind I threw a barrage of questions at the inspector about the integrity of the analysis and how could he be sure that iridium had been found. He could not answer any of the questions with confidence and he had not even the slightest idea of what I was asking when I asked him to quote the detection limit of iridium for the hand-held XRF he used for the analysis. The detection limit being the lowest quantity of a substance (in this case iridium) that can be distinguished from the absence of that substance within a stated confidence limit. Every analyst doing trace element should at least understand this and be able to quote the detection limits for the analytical instrument they are using. A hand-held XRF would be effective for say, determining whether confiscated metal bars or ingots were made of pure cast iron or pure iridium. In this case the concentrations of the metals making up these materials are in the very high per cent levels and in this sort of application the hand-held XRF can be effective and I can see why Customs make use of them. However to use an instrument of such limited analytical capability in an attempt to detect trace elements and then still base their decisions on whether to impound a specimen or not on their sketchy results is ludicrous! The analysis report of the DPMR (see below) concludes that the specimen contains 3.45% iridium, 0.49% rhodium, 0.37% gold, 0.31% palladium and 0.13% of ruthenium! The iridium concentration they report is therefore more than 8 million times higher than iridium levels found in the Bushveld Complex! One can make the same conclusions of the other precious metals. After 3 months of receiving the notification that the specimen was to be impounded and after having to provide an affidavit that I would only use the specimen for “display” purposes I was issued with a letter (see below) allowing me to be in the possession of the specimen. From the time of placing the order with the buyer to claiming the specimen took a period of 7 months. The letter concludes that “the amount of precious metals in the specimen would make the extraction non-viable”. Gee, at the levels of precious metals they found I should give up mineral collecting and head for Pasto Bueno in Peru and start mining the richest precious metals deposit on the planet!

The mineral specimen impounded by SA Customs for having 3.45% Iridium and other precious metals

*Additional information on Iridium:
How abundant is the element iridium on Earth? Iridium is a "platinum-group" metallic element that is very rare in the earth's crust. The platinum-group metals include platinum, iridium, palladium, rhodium, ruthenium, and osmium. In the Periodic Table of the Elements, these metals are also in the same columns as the Group 8 elements, which include iron, nickel, and cobalt. Group 8 elements all have a natural chemical affinity for each other, and therefore they tend to collect together in nature. The greatest concentration of iron on Earth is at its core. This is also where the greatest concentration of our planet's iridium resides. When our planet was still forming iridium and iron formed an alloy and sank into the interior of the planet forming its core. At the surface of the Earth, there are only a few environments that contain more than a trace of iridium. Volcanic and plutonic rocks that are rich in iron minerals, such as peridotite, some basalts, and some gabbros, occasionally contain enough platinum-group metals to be profitable to mine. However, these ores are rare. The Bushveld complex in South Africa is one of these rare orebodies that is host to relatively high precious metal concentrations and even then these are at the parts per billion level. In a typical analysis of the Bushveld Complex rocks bearing iridium, this element is only at an average of around 4 parts per billion or 0.0000004%. Iridium is even rarer in sedimentary rocks - in a randomly selected rock weighing one gram, the amount of iridium contained within it would be less than 1 billionths of a gram (1 nano gram). In fact, the amount of iridium is often so low that it sometimes cannot be measured at all using today's scientific equipment without making use of special pre-concentration techniques.

References:

1. Robin, E., L. Froget, C. Jehanno, and R. Rocchia. 1993. Evidence for a K/T impact in the Pacific Ocean. Nature 363:615-617

2. Alvarez, L.W., W. Alvarez, F. Asaro, and H.V. Michel. 1980. Extraterrestrial cause for the Cretaceous-Tertiary boundary extinction. Science 208:1095-1108.

3. Kerr, R.A. 1996. A piece of the dinosaur killer found? Science 271:1806.

4. Kyte, F.T. 1998. A meteorite from the Cretaceous/Tertiary boundary. Nature 396: 237-239.

5.Email correspondence with Prof. Bruce Cairncross and Bushveld PGM concentrations.

6.Michael J. Benton. When Life Nearly Died – The Greatest Mass Extinction of all Time

Crystal Healing, Pink Unicorns and the Tooth Fairy

2011-01-05T22:05:00.000-08:00

How serious do we take the claims of ‘crystal healers’ whose practice and influence in the mineral and gem world has taken on profound proportions? In recent years there has been a proliferation of the metaphysical and esoteric use of minerals and “crystals” supposedly for the enhancement of health and the treatment of disease. Mineral and gem shows are becoming increasingly dominated by “crystals” for healing purposes. Crystal healing practitioners use terms like 'energy' and they use it to cover anything that they can't explain any other way - such as 'energies unknown to science'. Do the claims of ‘crystal healers’ stand up to scientific scrutiny or is ‘crystal healing’ just another fashionable pseudoscience amongst a plethora of New Age hocus-pocus? Skeptics may be puzzled by the ready tendency of human beings to accept claims without sufficient evidence.

The late great Carl Sagan (1995) warned that there are “already many signs that modern culture may be on the verge of abandoning science for mysticism, and thereby sliding back almost without noticing it into superstition and the darkness that engulfed our demon-haunted world for thirteen centuries after the fall of Rome”. There also appears to be accelerated growth in anti-science in modern culture says renowned, skeptic, Paul Kurtz (2010) “It is paradoxical that today, when the sciences are advancing by leaps and bounds and when the earth is being transformed by scientific discovery and technological applications, a strong anti-science counterculture has emerged”

The rise of ‘New Age Science’ in recent years appears to govern the media which is filled with gobbledygook such as: tarot cards, quack medicine, magic waters, palm reading, UFO abduction, crystal healing, telepathy, astrology, conspiracy theories etc.... the list goes on and on. ‘New Age Movement’ literature in bookstores has grown to such an extent that books on the subject(s) outnumber books on science by a ratio of 10:1 (Hawkins, 2010). One possible reason for the proliferation of the ‘New Age Science’ may be that anyone can conjure up yet another madcap theory with absolutely no scientific evidence to support their theory and gets a cult following. In recent years, particularly with the rise of the New Age movement, myths concerning the healing powers of crystals have been introduced to society. Crystal healing practitioners claim to use ‘crystal energy', ignoring the fact that 'energy' has a very precise meaning in science. And they use it in an all-encompassing way to cover anything that they can't explain any other way - such as 'energies unknown to science'. Proponents claim that the healing properties of crystals rely on 'energy' that crystals are supposed to give off and that this energy exerts elusive influences on the body, realigning the body’s 'energy' into more harmonious, natural and healthy patterns (Willis, 2010). Here’s a quote from one of the many ‘Crystal Healing’ web sites [5.] giving an explanation on how to ‘select’ and ‘use’ a crystal for healing. “Crystal therapy involves the use of precious semi precious stones. These stones hold positive energy and act as a conduit for healing from the practitioner to the recipient. The stones also generate a healing vibration that heals on all levels, physical, spiritual, mental, emotional. A stone can be placed on the part of the body you would like to heal. A stone can also be placed on acupressure points. Generally therapists use quartz for physical healing amethyst for spiritual healing and rose quartz for emotional issues. There are many other crystals which carry a very specific healing vibration. They can pin-point complex healing issues & bring about healing & balance”

So, we are lead to believe that crystals allegedly affect the emotions and can be used not only for physical healing, but for emotional problems as well. Moreover, the claim goes further in boldly stating that crystals not only help with self-expression, and if that is not all …… creativity, meditation, AND the immune system! These claims are extraordinary. None of these assertions is backed by any scientific evidence – we just have to have faith and believe it! Extraordinary claims require extraordinary evidence. Everything about these claims should be skeptically examined and a demand for validation and verification be sought from the claimant. However, the burden-of-proof lies with those making the claim! Science has not identified any energy that could possibly be the healing energy claimed by crystal healers. Some crystal healers claim that the energy responsible is the piezoelectric effect, which is known to science. The piezoelectric effect can only be generated with a crystal that has been sliced into a thin section at specific orientations to the crystal axes and most types of crystals that crystals healers use cannot generate a piezoelectric effect anyway. Crystal healings may offer some assistance to some ailments, particularly emotional or psychological disturbances, but these healings are achieved as psychosomatic responses rather than through any direct effects from the properties of a crystal (Hawkins, 2010). The ready tendency of human beings to accept claims without sufficient evidence is wholly evident in the ‘New Age Movement’ and this includes ‘crystal healing’. Customers purchasing crystals from crystal healers often completely misunderstand the nature of what 'energy' means. In this way the customers are convinced, because the “effects” of the “energy” sounds good, without actually knowing anything about it and they take the word that the sellers are telling the truth and let’s not forget it’s good for sales. You can hang a tourmaline crystal around your neck, place quartz under your pillow, drink your mercury-laced cinnabar elixir and say it's providing health-giving energies, or 'cleansing energies' - whatever you please. What is being claimed has no scientific basis at all.

Many minerals species are potentially toxic - there are about 200 known radioactive minerals that contain uranium, thorium, or both elements [6.] and a large number are made up of heavy metals such as lead and mercury as in galena and cinnabar, respectively. I was horrified to hear a crystal healer practitioner announce with grand authority that realgar (an arsenic sulphide mineral, typically bright red in colour) can be used as an ‘elixir’ to promote a youthful appearance by boiling the mineral in water and drinking the water afterwards! “The red colour will vibrate with the root chakra!” she pronounced. Well I wonder how many of her customers were pronounced dead after drinking such a concoction!

As a scientist and a collector of minerals, I am unsympathetic to ‘crystal healing’ because it actively debauches the scientific enterprise, more so the disciplines of geology and mineralogy. And, even though all crystal healers and mystics will stand up and shout that “crystal healing works!” is not evidence that it does. Crystal Healing belongs in the same category as pink unicorns, Santa Claus and the tooth fairy. As modern culture is seemingly abandoning science and reason and accommodating mysticism there is an even greater need to question the validity of claims by following basic scientific methods of observation, independent testing, rational deduction, and verification by means of abundant evidence. We need to fight the misuse of science and praise the real wonder of science and avoid the ‘New Age’ taking us into a new ‘Dark Age’.

Quartz crystal from Rosh Pinah mine, Namibia. Photograph:A.Fraser

Cluster of clear quartz crystals (7 cm) from Rosh Pinah mine. Photograph:A.Fraser

References:

1. Sagan C. (1995). “The Demon-Haunted World - Science as a Candle in the Dark” (New York: Random House, 1995).

2. Kurtz P., (2010), “Exuberant Skepticism”, Prometheus Books, page 61

3. Hawkins C., “Crystal healing does it work?” http://www.helium.com/items/435008-crystal-healing-does-it-work (date accessed: 24 Dec 2010)

4. Willis P., “The Correx Archives” http://www.abc.net.au/science/correx/archives/crystal.htm (date accessed: 24 Dec 2010)

5. Donaldson R., http://www.helium.com/items/224162-crystal-healing-does-it-work (date accessed 29 Dec, 2010)

6. McGraw-Hill Science & Technology Encyclopedia: Radioactive Minerals http://www.answers.com/topic/radioactive-mineral (accessed 31 Dec, 2010)

Banded-Iron Formations: Clues to Early Earth’s Environment

2011-01-05T21:45:00.000-08:00

The Banded-iron formations give us clues to the atmosphere of early Earth. As we look deep into the Earth's past, evidence from old rocks suggests that environmental conditions were once very different. In particular, rocks making up the Banded-iron formations indicate that the early atmosphere contained little or no oxygen.

The picture in figure 2 below shows an excellent example of Banded-iron formation (BIF). Most BIFs are strikingly colourful with the dark layers being made up mainly of the iron oxide minerals, hematite (Fe2O3) and magnetite (Fe3O4) and red layers of jasper, a variety of chalcedony, or very fine-grained quartz (SiO2) (Mathez, 2006). BIFs are rocks of the Proterozoic Era ranging from 1.8 to 2.5 billion years in age and consist of alternating iron-rich and iron-poor layers, typically only millimeters to centimeters thick [2]. Banded iron formations are found throughout the geological record, but the period from 2.5 to 2.0 billion years represents a unique time in Earth history, a time during which 92% of the Earth’s BIFs were laid down (Immenhauser, 2005). For this enormous accumulation of iron oxide to have occurred over such a vast time span meant that something about the chemistry of early earth was very different to what it is today. The chemistry of rocks from the Proterozoic shows that oxygen was a rare gas in the atmosphere. The key to understanding the chemical reactions occurring in the early oceans is in the relationship between the elements oxygen and iron. Iron forms two ionic states, namely, ferrous (Fe+2) and ferric (Fe+3) – the +2 or +3 indicates the extent to which iron is oxidised. Iron will only dissolve in significant quantities in water that contains no oxygen (anoxic water). In anoxic water iron dissolves in the ferrous state as ions of hydrous Fe2+, or FeOH+ (Mathez, 2006). Therefore, in order for iron-rich chemical precipitates to form, the early oceans must have been sufficiently anoxic to dissolve iron. Since the ocean and atmosphere exchange oxygen rapidly, the atmosphere could not have contained much oxygen, either. But oxygen was in the making; photosynthesis from blue-green bacteria dominating the early oceans would have created a net gain of oxygen first in the ocean and later in the atmosphere (Attenborough, 2010). Ferrous iron in oceanic water scavenged oxygen that was a waste product for the photosynthesising bacteria and rained down onto the ocean floors as rust coloured chemical sediment. This was chemistry on a grand scale – the soluble ferrous iron was being oxidised to insoluble ferric iron as the minerals, magnetite and hematite. At the same time, primitive photosynthetic blue-green algae were beginning to proliferate near surface waters. As the algae would produce molecular oxygen (O2) as a waste product of photosynthesis, this free oxygen would combine with the iron in solution to form iron oxides. “As the biomass expanded beyond the capacity for the available iron to combine with waste O2, the oxygen content of the sea water rose to toxic levels for the algae population and resulted in their large-scale die-off, which in turn gave rise to an iron poor layer of silica on the sea floor” [2.]. As time passed and algae populations re-established themselves, a new iron-rich layer began to accumulate on ocean floors. This cycle was repeated and continued for hundreds of millions of years. “Each band in the iron formation is similar to an annual layer of sediment – or varve - to the extent that the banding is assumed to result from cyclic variations in available oxygen” (Kirschvink, 1992). For over 2 billion years this went on, until the iron in earth’s oceans was depleted. Since there was no iron left in solution the excess molecular oxygen bubbled up into the atmosphere and began accumulating from about 1700 million years ago, after two-thirds of Earth history [6.]. The vast layers of iron minerals stayed behind in the Banded-iron formations. The rise in the levels of oxygen after the massive depletion of iron meant that photosynthesising bacteria would face near extinction as oxygen is a reactive and highly toxic gas (Southwood, 2003). Cells would have to adapt to this change in environment and the excess oxygen would ultimately lead to the formation of an ozone layer and the proliferation of new life forms in an oxygenated world during the so-called “Cambrian Explosion”. But that is the subject of another article! Banded-iron formations occur in many parts of the world and constitute the major reserves of iron ore. At Thabazimbi and Sishen these reserves are exploited by major mining operations.

Figure 1: Core sample (8 cm) of Banded iron-formation from Hamersley, Australia. A fault runs through the center of the specimen showing the displacement of the individual layers of banding. Specimen and photograph: A. Fraser

Figure 2: Banded iron-formation (6 cm). Banded iron-formation is composed of alternating layers of iron-rich material and silica (chert), N’chwaning II mine, Kalahari Manganese Field. Each layer is relatively thin, varying in thickness from about a millimetre up to a few centimetres. This is evidence of aerobic life altering the early earth’s atmosphere by the precipitation of iron oxides. Specimen and photograph: A. Fraser

Figure 3: Banded iron-formation (10 cm). Banded iron-formation is composed of alternating layers of iron-rich material, Northern Cape,, South Africa. Specimen and photograph: A. Fraser

Figure 4: Banded iron-formation (14 cm). Banded iron-formation is composed of alternating layers of iron-rich material, Thabazimbi, South Africa. Specimen and photograph: A. Fraser

Figure 5: Mining activity at the Thabazimbi iron ore mine. Photograph by A.Fraser

References:
1. Attenborough. D., (2010). “First Life” Harper Collins publishers, ISBN 978 0007365241. (page 46)
2. “Banded Iron Formation” http://jersey.uoregon.edu/~mstrick/RogueComCollege/RCC_Lectures/Banded_Iron.html (accessed Dec 27, 2010)
3. Kirschvink, J. (1992). "Late Proterozoic low-latitude global glaciation: the Snowball Earth", in J. W. Schopf; C. Klein: The Proterozoic Biosphere: A Multidisciplinary Study. Cambridge University Press.
4. Mathez, E. (2006). “How Has the Earth Evolved? Evolution of the Atmosphere”
5. McCarthy, T. 2009. How on Earth? Answers to the puzzles of our planet. Struik Nature, Random House Struik (Pty) Ltd, Cape Town
6. http://www.amnh.org/learn/resources/earth_resource1.php (accessed Dec 27, 2010)
7. Southwood. R., (2003) “The Story of Life” Oxford University Press (Pages 22- 24).

What Makes a Good Analytical Chemist?

2010-12-06T05:27:00.001-08:00

What makes a good analytical chemist? This was a question I was asked recently while giving a course on method validation. The question was somewhat of a challenge to answer ‘off the cuff’, however, it lead to an interesting excercise amongst the course delegates and to the formulation a number of attributes that would make a good analytical chemist. These include; intellectual curiosity, a passion for science, self-confidence, solid work ethic, drive, committment, good time management, perseverance, determination, patience, self-motivated and a strong desire to succeed. Additionally it was felt that a good analytical chemist needs to work and think independently, work well with others and be a good problem solver and understand that problem solving is a process, not something memorised. A few days later, after some deliberation I added to the list of attributes and believed that a good analytical chemist needs to be knowledgeable in all areas of chemistry, and able to integrate their knowledge across all areas of science, within and beyond chemistry. Good quantitative and reasoning skills and an ability to grasp difficult concepts and reduce them to an understandable foundation I feel are vital attributes. As we all know problems arise in the laboratory and a good analytical chemist needs to be an excellent problem solver. Communication in terms of good oral and written communication skills is vital as the analyst needs to be able to articulate their knowledge and thought processes to others. I’d be happy to hear your views!

Fossil Collecting in Italy

2010-11-07T10:06:00.000-08:00

By Allan Fraser

On an annual basis my wife and I take our holidays in Italy and this year was no exception. On our way to the Euro Mineral Show in Turin, we spent a few days in the the Piedmont area near the town of Asti enjoying the good food and exceptional wines. Besides being a country of immense beauty one also gets a deep sense of the human history when visiting Italian cities and travelling through the countryside. Most Italian cities are built on Roman foundations and Roman roads are still used to a large extent today. But human history is but one ancient part of Italy. About 2 - 5 million years ago, most of the low-lying regions of Italy were covered in a shallow warm sea. The evidence of this ancient sea can be found in many regions of Italy as inland beach sands, clays and other marine rocks along with a variety of marine fossils. In the northwest region of Italy, particularly in the Piedmont area, ancient beach sands dominate the landscape having formed small round hills.

Whilst visiting a guest farm near the town of Asti in Piedmont we discovered a cliff made of this ancient beach sand and we were amazed to see numerous fossil shells protruding from the compacted sand. We were able to extract several of these fossils which were easy to clean of the sand to expose the fossilised shells. We collected about a dozen and left those behind that were not complete or showed some damage. Later a literature search indicated that the shells we had found were of the species Pecten Nigromagnus and those they had lived about 3 to 5 million years ago during what Earth Scientists call the Pliocene period. I took pictures of the fossils (shown here) before donating them to the Piedmont Paleontological Society.

Self-Evaluation - A Desirable Philosophy for the Analytical Chemist

2010-09-16T09:12:00.000-07:00

A good analyst continually tempers his or her confidence with doubt. Such doubt leads stimulates a search for new and different methods of confirmation for reassurance. Frequent self-appraisals should embrace every step – from collecting samples to the reporting of results.

The analyst’s first critical scrutiny should be directed at the entire sample collection process in order to guarantee a representative sample for the purpose of the analysis and to avoid any possible losses or contamination during the act of collection. Attention should also be given to the type of container and to the manner of transport and storage.

A periodic assessment should be made of the available analytical methods, with an eye to applicability for the purpose and the situation. In addition, each method selected must be evaluated by the analyst for sensitivity, precision and accuracy, because only inn this way can he determine whether he has interpreted the directions properly. Self-evaluation on these points can give the analyst confidence in the value and significance of his reported results.

2010-07-17T10:50:00.000-07:00

Here are a few of my favourite quotes by the late great American astronomer, Carl Sagan (1934-1996).

"Modern science has been a voyage into the unknown, with a lesson in humility waiting at every stop. Many passengers would rather have stayed home"
Carl Sagan, Pale Blue Dot

"The method of science is tried and true. It is not perfect, it's just the best we have. And to abandon it with its skeptical protocols is the pathway to a dark age"
-- Carl Sagan

"For years I've been stressing with regard to UFOs that extraordinary claims require extraordinary evidence"
-- Carl Sagan, quoted from Billions and Billions, chapter 5 ("Four Cosmic Questions"), page 49

"If some good evidence for life after death were announced, I'd be eager to examine it; but it would have to be real scientific data, not mere anecdote.... Better the hard truth, I say, than the comforting fantasy"-- Carl Sagan, The Demon-Haunted World, page 204

Minerals from Peru - new additions to my Mineral Collection!

2010-03-26T01:24:00.000-07:00

Bournonite after Tetrahedrite with Quartz (~7 cm) from a new find at Mundo Nuevo mine

A large manganoan calcite crystal with pyrite on tetrahedrite. From the famous Casapalca mine

Orange orpiment with barite, Quirivilca mine

A large Manganoan Calcite ~13 cm with calcite and sphalerite from Racrachanca mine.

Purple Coquimbite (~6 cm) from Peru

Sphalerite with calcite (~8 cm) from Ticlio mine

These are a number of new mineral specimens added to my growing collection of minerals from the country of Peru. The new bournonite pseudomorph after tetrahedrite from Mondo Nuevo specimens are particulary intruiging and are just one of many fascinating pseudormorphs from Peru. The Sphalerite with calcite specimen from Ticlio mine has to be one of my favourites. There is a "shelf" of fine calcite in the center of the specimen that has several spheres of sphalerite on the shelf. The sphalerite have a dark blue iridescence which makes the entire specimen especially attractive!

Allan

African Rainstorm in the Waterberg

2010-02-16T06:19:00.000-08:00

Late last year I visited the Waterberg area of South Africa. I was standing on a ridge overlooking a thunderstorm moving over a distant plain. The pictures above show the progression of the storm over about a half hour. The area is pristine and typical of the Waterberg area with thorn trees and low lying hills. I imagined that this scene would have been been witnessed by Australopithecus africanus or Homo Erectus as they looked over a similar landscape millions of years ago.

The hills in the distance are 1.6 billion year old sedimentary rocks called the Waterberg Supergroup rocks which are a sequence of conglomerates, sandstones and shales. Read more on the Waterberg rocks at http://www.onlineminerals.com/geo.htm

Allan

February 16

Scientists Rally against Creationists

2010-02-15T11:49:00.000-08:00

The young Charles Darwin

Scientists rally against creationist 'superstition'

To mark a double anniversary celebrating Charles Darwin, the father of evolution, his supporters are taking the fight to their opponents The rise of creationism in Britain to the point where four out of 10 Britons believe it to be the literal truth – as well as the idea being taught in state-approved schools – has spread alarm throughout the scientific community. But this week sees the start of a concerted fightback, as an 18-month celebration of evolution and its greatest proponent, Charles Darwin, gets under way, marking the 150th anniversary of the unveiling of his theory and the 200th anniversary of his birth. People all over Europe will take part in a mass experiment to discover evolutionary changes to a species of snail; a major series of programmes is to be shown by the BBC; several books are to be published; and the Open University plans a new course on the subject. Entries for a competition to design "Darwin's Canopy" – a piece of art to cover a ceiling in the Natural History Museum – will be unveiled this week, and the museum will hold a major exhibition on Darwin beginning in November. Dr Bob Bloomfield, head of special projects at the museum and a key figure in the "Darwin200" project, said he was concerned by the prevalence of creationist ideas.

"The statistics in this country are quite frightening. If you add up the percentages that either believe in creationism or intelligent design, it is approaching 40 per cent," he said. "I don't think society can be complacent when ideas which are unsound are perpetrated. We are trying not to compromise people's faith views, other than where they are absolutely inconsistent with science." He said the teaching of creationism in schools was "very problematic". Professor Jonathan Silvertown of the Open University, who is writing a book entitled 99% Ape: How Evolution Adds Up, said the OU would be running a course called Darwin and Evolution. "The idea is to give people a feel for the modern evidence," he said. He and the geneticist Professor Steve Jones, of University College London, are involved in a mass science project to study changes in banded snails, by recruiting tens of thousands of people across Europe. Professor Jones said religious students – even those studying medicine – were becoming increasingly vocal in their opposition to evolution, saying he was "telling lies and insulting people's religion" by teaching the subject. "They want permission not to come to those lectures and sit those exam questions," he said. "I have been teaching genetics and evolutionary biology for 30 years and for the first 20 I think the issue arose once. That's changed."

Reposted from : http://www.independent.co.uk/news/science/scientists-rally-against-creationist-superstition-837832.html

Pale Blue Dot

2010-01-26T07:20:00.000-08:00

No one could put it more heartfelt and passionate than Carl Sagan could. Listen to Sagan's narration from his book the Pale Blue Dot.

http://www.youtube.com/watch?v=p86BPM1GV8M

It is Natural and not Supernatural

2010-01-26T06:04:00.000-08:00

The recent earthquake in Haiti has many religious people proclaiming that the reason for every disaster is sin. While Haitians may not blame past sins for the earthquake, many people have a worldview in which disasters are the result of God punishing humanity. Numerous Haitians gave thanks to God for keeping them alive. They believed that what happened was the will of God.

If an all-powerful god either caused the earthquake in Haiti or stood passively by as thousands perished, he would be a god more worthy of blame than praise. Some days the best thing you can say about God is that he doesn't exist.

The theory of plate tectonics is a starting point for understanding the forces within the Earth that cause earthquakes. Plates are thick slabs of rock that make up the outermost 100 kilometers or so of the Earth. Geologists use the term "tectonics" to describe deformation of the Earth's crust, the forces producing such deformation, and the geological and structural features that result.

It took only a few generations of scientists before there was a workable theory of plate tectonics. We live on a planet with a hot interior that is insecurely coated with a thin crust of grinding tectonic plates. Earthquakes and tsunamis are to be expected and can even to some degree be anticipated. It's idiotic to ask whose fault it is. The Earth's thin shell was quaking and cracking billions of years before human sinners evolved, and it will still be wrenched and convulsed long after we are gone. These geological dislocations have no human-behavioral cause. The believers should relax; no educated person is going to ask their numerous gods "why" such disasters occur. A fault is not the same as a sin.

Earthquakes occur only in the outer, brittle portions of these plates, where temperatures in the rock are relatively low. Deep in the Earth's interior, convection of the rocks, caused by temperature variations in the Earth, induces stresses that result in movement of the overlying plates. The rates of plate movements range from about 2 to 12 centimeters per year and can now be measured by precise surveying techniques. The stresses from convection can also deform the brittle portions of overlying plates, thereby storing tremendous energy within the plates. If the accumulating stress exceeds the strength of the rocks comprising these brittle zones, the rocks can break suddenly, releasing the stored elastic energy as an earthquake.

Science works whether you believe in it or not.

Ancient carbonate deposit and stromatolites

2010-01-20T06:45:00.000-08:00

In 2008 a group of us visited Pering mine near Kuruman. Besides the very interesting minerals we collected the geology was fascinating.

The Pering deposit is a carbonate (limestone/dolomite) hosted zinc-lead mineralized breccias within the Campbell Rand member of the Ghaap Group, Transvaal Super Group (classified as the oldest Mississippi Valley Type (MVT) economic deposit in the world. It has been dated at approximately 2,550my old (Paleo-proterozoic in age), while all the other MVT deposits in the world are younger, ranging from middle Proterozoic (1,200my) to Jurassic (175 my) in age. For this reason Pering is unique and deserves more attention from a mineral collector’s point of view.

One could get a glimpse into the fascinating development of this unusual deposit as we drove down the ramp road into the large pit. The upper layers of dolomite still have well preserved stromatolite domes some as large as 5 metres across, with intercalated thin shale layers within the thick units of dolomite. These lower dolomites are characterised by smaller domed deformed stromatolitic lenses in the lower section of the exposures in the opencast pit. Stromatolites were simple algae-like plants requiring a warm shallow marine sea to thrive. These fossils represent the oldest living organisms on the planet, peaking about 1250 million years ago. These cyanobacteria are thought to be responsible for increasing the amount of oxygen in the primeval earth’s atmosphere through their photosynthetic action of taking in carbon dioxide and dispelling oxygen as waste (Allwood, et al, 2006).

Evidence of several fluctuations in sea-level resulted in the formation of limestone and dolomite deposits in deeper waters, with thin shale layers forming during shallow lagoonal/esturine conditions. Fossil ripple marks along bedding planes in the thin shale layers were evident at many of the collecting sites, indicating shallow gentle tidal flow when these sediments were deposited in the inter-tidal zone. These abrupt changes in sedimentary units were clearly visible on the mining benches as we explored the cliff-like rock walls of the open pit for pockets where we might be lucky to find mineral specimens.

Magnificent Desolation

2010-01-07T08:49:00.000-08:00

Buzz Aldrin uttered "Magnificent Desolation" on seeing the surface of the Moon for the first time. There are many parts of our planet that resonate with me and I can describe as "Magnificent Desolation". I have added a few pictures here on some of the places that I have seen that would earn the title of "Magnificent Desolation".
Pictures from the top down: Peruvian Andes, Peruvian Andes with limestone cliffs, Rosh Pinah region in southern Namibia. More pictures to come.

Ancient Earth - Evidence in the Greenstones

2010-01-07T02:13:00.000-08:00

I have for a long time been fascinated and intruiged with the formation of old rocks(especially Archean rocks and continental crust). I have read everything one can possible read on the subject and for a non-geologist like me I have still have many questions. I live very near to a number of greenstone remnants here in Johannesburg and only a 5 hour drive from Barberton where major outcrops occur.

From what I can gather; The oldest piece of continental crust dated so far is the so-called Acanasta-Gneiss from the Slave Province in NW Canada (4.06 Byr. old).

Nevertheless, it is now assumed that fragments of older solid parts of the earth consisting of the crust and outer mantle and liquid water existed long before the Acanasta-Gneiss. This is evidenced in the oxygen isotope 0^18 record in zircons (small zirconium oxide crystals that resist weathering very well). According to recent research, Earth between 4.4 and 4.0 was not a magma-red glowing hostile planet but a place covered by tranquil oceans with small islands protruding from these waters. (I'll discuss the oxygen 18 isotope and zircons in a later blog).

Mean temperatures were – from a geologic point of view – cool, i.e. in average about 200oC or somewhat less. Beneath this value, a portion of the water, previously only existing as vapour, condensates under the high pressure conditions and formed oceans. The scarcity of previous continental fragments is probably the result of the so-called late heavy bombardment at about 3.9 Ga., one of the main meteoric bombardments of the young Earth.

Areas underlain by Archean rocks are typified by two main types of rock bodies: ‘greenstone belts’ and ‘granite-gneiss complexes’. Other cherts and iron-rich sediments, known as banded iron formations, are also found in the Archean sedimentary belts. For example, Zimbabwe consists of mostly of gneiss and various granitic rocks; the remaining rocks are largely greenstone belts.

The oldest large, well preserved greenstone belts are those of South Africa, which date from 3.6 billion yrs. An idealized greenstone belt consists of three major rock units: the lower and middle units are dominated by volcanic rocks and the upper unit is sedimentary. The volcanic rocks of greenstone belts are typically greenish (see above pictures of greenstone rocks from Johannesburg area) due to their low grade metamorphism (chlorite minerals). The occurrence of pillow basalts in the Barberton region indicates that much of the vulcanism responsible for the igneous rocks of the greenstone belts was subaqueous; shallow water and subaerial eruptions are indicated by pyroclastics.

Sedimentary rocks are a minor component in the lower parts of greenstone belts but become increasingly abundant towards the top. The most common ones are successions of graywacke (sandstone containing clay and rock fragments) and argillite (slightly metamorphosed mudrocks). Small-scale graded bedding and cross bedding indicate that the graywacke-argillite successions are deposits of ancient turbidity currents. Others were deposited in deltas, tidal-flats, barrier islands and shallow marine shelf environments.

In summary, detrital Archean rocks seem to indicate the presence of basins of moderate depth flanked by volcanoes that spewed out lava.

Rock of Ages

2010-01-05T09:38:00.000-08:00

We were at dinner on the 31st December with a group of friends overlooking the horizon with the full moon rising. It is a "Blue Moon" my wife said. That got us talking about the moon and we got onto the subject of the lunar rocks brought back by the Apollo Missions and that lead the coversation to how to how old the moon was.

Well, the abundances of radioactive elements in rock samples can be used to tell the age of the rock in a process called Radioactive Dating. The lunar material was analysed and samples from Mare Imbrium and the Ocean of Storms brought back by Apollo 11 and Apollo 12 are about 3.5 billion years old, which is comparable to the oldest rocks found on the surface of the Earth.

What is interesting is that the ejecta blanket from the Imbrium Basin (which was formed by a gigantic meteor impact) was returned by Apollo 14 and found to be about 3.9 billion years old.

However, Lunar Highlands rocks returned by Apollo 16 are about 4 billion years old. The oldest lunar rock found was located by Apollo 17 and appears to be about 4.5 billion years old. So, the oldest material from the surface of the Moon is almost as old as we believe the Solar System to be. This is more than a billion years older than the oldest Earth rocks that have been found. Thus, the material brought back
from the Moon by the Apollo missions gives us a window on the very early history of our Solar System that would be difficult the find on the Earth, which is geologically active and has consequently, obliterated its early geological history.

The amount of cratering is usually an indication of the age of a geological feature. But more of this in a future blog.

Allan

Minerals, Rocks and Rationality

2010-01-05T06:12:00.000-08:00

I am a collector of minerals and rocks. A recent acquisition of mine is a number of specimens of Albite with Quartz and Sphalerite from Rosh Pinah mine in the south of Namibia. On first seeing these specimens, I assumed that the white crystals were calcite, but looking a bit closer they seemed to be something different. I removed a small section of a crystal from the back of one of the specimens and had it identified by XRD for crystal structure and SEM for it's chemistry. Both techniques confirmed that the mineral is albite. This came as a surprise as the albite is typically found in volcanic and metamorphic rocks and not (or rarely) in sedimentary rocks as is the case at Rosh Pinah. I did some research on this and consulted several geologists and the consensus is that the albite crystals could have been formed in a late diagenetic stage at low hydrothermal temperature and be related to hydrothermal post-ore fluids. So, this was as far as I know the first find of well crystalised albite from this mine and also perhaps the first time it has been positively identified by proven scientific means from this locality.

Allan

In the Valley of Iridium

2010-01-05T04:38:00.000-08:00

pics: The K-T site at Gubbio showing the Cretaceous (lower grey limestone), the thin 1 cm layer of iridium rich clay in the middle and the darker brown clay of the Tertiary period. The Valley of Iridium - the Bottaccione Gorge near Gubbio.

5 Jan 2010

It’s 2010 and another circuit around the Sun begins. It’s traditional to take this time to look back, and to look ahead. Looking back at 2009, one of the highlights for me was to visit the K-T boundary at Gubbio. Looking forward I'd like to learn as much as possible about this geological event.

I had the privilege last year to visit the world-famous K-T boundary site in Italy. It has been an ambition of mine to visit this site since reading about it in Time magazine in the early 1980’s. I was so intrigued by the site and the history of its discovery that I spent a part of my Italian holiday preparing a write-up on it. Back home in my study, in a moment of utter madness I decided to try and calculate the diameter of the meteor that had caused the K-T extinction and the energy released from the impact. I struggled through the calculations, and after a week of frustration and ludicrous answers, I finally succeeded in the math. Turns out that my knowledge of the metric system was pretty poor! The numbers show that the effects of an impact of this size were of global proportion as it produced enormous amounts of energy, molten rock and dust and caused almost incomprehensible destruction.

Here are the numbers:

Why would a meteor impact, even one as large as the Chicxulub feature, be enough to cause the extinction of the dinosaurs and a myriad of other species? We could perhaps get a better understanding of this by attempting to answer questions such as; how much material was ejected at the time of impact, how much iridium was distributed worldwide, how much did the meteor weigh and what was its diameter and how much energy was released during the impact? In an attempt to quantify these parameters I did a number of calculations using the estimated impact velocity, the average iridium content and mean thickness of the KT layer. The answers I got even with making several assumptions revealed staggering numbers. I give detail of the calculations and answers below:

(note: this crazy html text does not allow the superscript function, so I have added the up arrow ^ to denote that the number is a superscript i.e. 1 x 10^2 would be 1 times ten to the power of 2).

How much material was ejected from the site of impact?
The Iridium layer is globally present on average as a 1 cm thick layer. The surface area of the Earth is 1.3 x 10^8 km^2. Since, area x thickness = volume, then 1.3 x 10^8 km^2 x 1 x 10^-5 Km gives us the volume ejected in Km^3:

The volume of material ejected by the impact is 5.1 x 10^12 Km^3

How does this compare with other known events?

If we compare the amount of material ejected by some of the largest volcanic events in recent geological time with that of the K-T meteor impact, we see that the K-T event produced 2 million times more ejecta than the supervolcano at Yellowstone.

Krakatoa (1883) produced 21 km^3 of material
Yellowstone “Supervolcano” (100 000 years ago): 1000 km^3 of material
Yellowstone “Supervolcano”(2 million years ago): produced 2500 km^3 of material.
K-T Chicxulub impact produced: 5.10000000000 km^3

How much Iridium did the meteor contain?
Using the average density of crustal rock which is 3000 kg/m^3 and the total K-T clay mass of 1.53 x 10^16 kg dispersed around the earth and the mean iridium concentration of 0.3 parts per billion in KT layer we can calculate the metric tons of iridium in the meteor as:

4.59 x 10^6 Kg (4590 metric tons)

How much did meteor weigh?
From the average iridium abundance in chondritic meteorites, the mass of the meteor is calculated at:

4.83 x 10^14 kg (4.83 x 10^11 metric tons)

What was the diameter of meteor?

From the density of C1 Carbonaceous Chondrites (2110 Kg/m^3) the volume of the meteor is calculated at 2.30 x 10^11 m^3 (or 2.3 x 10^2 Km^3)

Assuming that the meteor was spherical, we can calculate its diameter:

Diameter = 2(3^√2.3 x 10^2 x 0.75/3.14)

Diameter = 7.6 Km

Alvarez et al used four independent methods to calculate the diameter of the impactor. The mean value they obtained was 10 Km with a standard deviation of ± 4 Km. This puts my calculation of the diameter of the meteor within the standard deviation obtained by Alvarez et al. As a size comparison Mount Everest is 8.84 Km in height.

How much energy was released on impact?

A 7.6 km diameter meteor travelling at 25 Km/second has a kinetic energy of:

Ke = ½ mv^2 = 3 x 10^23 Joules
(where Ke is Kinetic Energy, m = mass of meteor and v is the velocity of the meteor)

Energy released on impact = 3 x 10^23 Joules

Comparing the amount of energy released by the Chicxulub impactor with the Hiroshima A-bomb which produced 8.4 x 1013 Joules of energy, we can calculate that the K-T meteor impact was equivalent of 3.5 billion Hiroshima atomic bombs! That is, 0.5 atom bombs for every person living today. A megaton of TNT is 4.184 × 1015 joules, therefore the Chicxulub impactor would have produced energy equivalent to 71 million megaton of TNT.

The discovery of the K-T iridium anomaly at Gubbio is considered to be one of the most important discoveries in evolutionary science. It was also central to the recognition by scientists that occasional catastrophic events like great impacts require a rejection of strict uniformitarianism in geology.

While the impact hypothesis is now one of the strongest and most widely-accepted theories about the extinction of the dinosaurs, other ideas remain valid, and it is highly unlikely the question will be definitively answered in the near future. Vulcanism could be a source of some of the iridium, but to have provided enough of this element to give the concentrations found uniformly worldwide in boundary clays, would have involved a degree of volcanic activity far beyond human comprehension. Even the basalts of the Deccan Traps in India, proposed by some to have been a source of such iridium, contain only 0.005 ppb of this element.

What is important to note, however, is that the death of the dinosaurs was the direct cause for the rise of mammals. Dinosaurs had their chance, and lost out to a group of small, furry animals that would evolve into the forms that now have dominion over the Earth. But that doesn't mean we're exempt from the same dangers. From research of craters on the Moon and Mercury, it is estimated that the time to collision is proportional to the square of the diameter of the object . Therefore, meteors of 10 kilometers diameter will collide with Earth on average once every 100 million years, meteors of 1 kilometer in diameter every 1 million years and 100 meter diameter meteor every 10 000 years.

So pause for a moment and look up—you never know what's coming.