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!

Sunday, November 7, 2010

Fossil Collecting in Italy

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.

Thursday, September 16, 2010

Self-Evaluation - A Desirable Philosophy for the Analytical Chemist

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.

Saturday, July 17, 2010

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

Friday, March 26, 2010

Minerals from Peru - new additions to my Mineral Collection!

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!


Tuesday, February 16, 2010

African Rainstorm in the Waterberg

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

February 16

Monday, February 15, 2010

Scientists Rally against Creationists

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 :

Tuesday, January 26, 2010

Pale Blue Dot

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.

Wednesday, January 20, 2010

Ancient carbonate deposit and stromatolites

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.

Thursday, January 7, 2010

Magnificent Desolation

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

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.

Tuesday, January 5, 2010

Rock of Ages

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.


Minerals, Rocks and Rationality

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.


In the Valley of Iridium

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.