Saturday, April 9, 2011
The Universe – Cause and Effect
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.
Sunday, April 3, 2011
Rock of Ages
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!
Sunday, March 13, 2011
Science Illiteracy – it’s just depressing
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.
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.
Friday, February 18, 2011
Your Mineral Specimen has been Impounded!
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
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
Wednesday, January 5, 2011
Crystal Healing, Pink Unicorns and the Tooth Fairy
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
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).
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).
Monday, December 6, 2010
What Makes a Good Analytical Chemist?
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!
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