Month: June 2023

Minerals are the building block of planet Earth. They are simply the essential fabric of our existence. For minerals to form you need the ingredients with which you build the minerals (i.e., elements), the right temperature and pressure conditions, space for the minerals to nucleate and grow out into, and time. When minerals are unique in terms of their color, rarity, clarity or have all of these desirable attributes; we call them gemstones.

Gemstones are beautiful, but gemologists have their own objective criteria of defining the most beautiful and desirable gems. In the world of gemology, the color, clarity, size, and cut of minerals determine their desirability. Among the most desirable gem is diamond. Interestingly, it is one of the minerals that was formed following the first supernova explosion. Nature’s arrangement of the bonding of the carbon atoms determines whether we get graphite or diamond. Carbon is the foundation of the organic life and seems to build fascinating wonders in both organic and inorganic worlds. In the Earth’s interior, diamonds are formed at a cratonic keel under immense pressure and temperature. We mine diamonds from kimberlite pipes. Kimberlite pipes are formed due to volcanic activities that bring deep-seated (200 to 300 km) melts and minerals including diamonds, olivine (this is also known as peridot), phlogopites, and carbonates to the uppermost crust. Given the relative rarity of diamonds, our recent capabilities of diamond mass production have been extremely helpful for both the jewelry and manufacturing industry. In 1954, Dr. H. Tracy Hall made the first synthetic diamonds. Dr. Hall was not only a great inventor but also a master of poetic descriptions. When he recollected on his discovery he said, “My hands began to tremble, my heartbeat rapidly, my knees weakened, and no longer gave support.” The GIA Museum in Carlsbad, California has a beautiful display of the diamond press (image below) and Dr. Hall’s discovery story, which also includes the above quote.

Much like diamonds, high-quality rubies, sapphire, and emeralds are highly sought after. From these, ruby and sapphire fall in the corundum group. The vibrant red variety of corundum, which sometimes are also referred to as pigeon blood rubies, command high prices. The red color of ruby is caused by impurities of chromium that substitute for aluminum. Without any impurities, corundum (Al₂O_3, aluminum oxide) is colorless. The vibrant blue variety of corundum is called sapphire. Iron and titanium impurities are responsible for the blue color. Corundum is the second hardest mineral, runner up to the hardest mineral ever discovered, the diamond. Ruby and sapphire are mined from pegmatite bodies and metamorphic terrains. In Asia, it is typical to find rubies within marble.

Emerald is a green variety of the beryl group. Its color is caused by impurities of chromium and vanadium. Emeralds almost always have internal fractures, and they are softer than corundum, but generally quite durable and harder than minerals such as quartz. Emerald is formed in both sedimentary and metamorphic environments. However, the prevalent emeralds are formed in environments where pegmatite intersect with schists. Emerald has a chemical composition that predominantly constitutes beryllium, silicon, aluminum, and oxygen.  

These popular gems are mined all over the world. Diamonds are mined from a few countries in Africa, Canada, Russia, and Australia. From these, if we consider the 2020 global diamond production, nearly 64% of the total production was from Africa. In the chart below, the name of the countries and their respective production are shown.

Rubies and Sapphire are mined from East Africa, Burma (now called Myanmar), Pakistan, Afghanistan, Sri Lanka, and Madagascar. Again, if we consider data published by National Resources Governance Institute (NRGI) in 2017, the ruby production in Africa appears to be higher constituting over 60 % of the total production (chart shown below). Sapphire production is increasing in African countries as opposed to countries like Australia where the trend shows a steady decline. Notably, the supply of sapphire from Asian countries is significant in both quality and quantity.  

Brazil, Zambia, and Colombia are the leading emerald producers (chart shown below). Over half of emeralds production is in Brazil and Colombia. Other countries such as Pakistan, Afghanistan, Israel, China, India, and Ethiopia are among other emerald producing countries.

As the production statistics show, a considerable amount of gemstones are produced in Africa. Africa, as a developing continent, should take advantage of these resources by building gemology knowhow, investing in mining and exploration, and creating cutting facilities. Proper environmental impact studies should be conducted to warrant a hospitable environment during and after mining. Organizations such as the African Union should also be involved in studying the proper economic potential of these resources and implementing continental policies that African countries could benefit from.

The advanced technologies and growing knowledge of mineral formation have created multiple methods of synthesizing gemstones for both commercial and industrial uses. These gemstones are continuously increasing in production for use in both jewelry and industry sectors. Creating alternatives and market interest due to their affordability. However, natural gemstones are still highly sought after and will continue to have prestige and desirability.  

Your friendly geologist, Luel

References

GIA Gem Encyclopedia | Complete List Of Gemstones

7.12: Causes of Color – Geosciences LibreTexts

List of countries by diamond production – Wikipedia

Global-Emerald-and-Ruby-Supply-Analysing-Market-Data.pdf (gemfields.com)

Geology – rocks and minerals (auckland.ac.nz)

Geology considers the immutability of fundamental physical processes across geologic time as one of its principles. This is widely referred to as the principle of uniformitarianism. The principle of uniformitarianism states that the present is the key to the past. Although seemingly simple, this principle has fundamentally revolutionized the science of Geology and considerably modified the philosophical fabric of society by particularly redefining the role of Time in geological processes. For example, uniformitarianism was used to challenge the notion that Earth is only 6000 years old. Simply put, its task is to observe, closely and keenly, the present physical processes in order to infer what might have happened in the past (e.g. examine basins in which sediments are depositing, theorize upon their accumulation and rock formation process, and apply the principles to better understand the formation of sedimentary rocks over millions of years). Accordingly, uniformitarianism accumulates knowledge and insights by starting from particulars and establishing their universals as theories and laws.  

However, like all things with value, uniformitarianism has its own limitations. Bertrand Russel illustrates this limitation eloquently by using his optimistic chicken as an example, “The man who has fed the chicken every day throughout its life at last wrings its neck instead, showing that more refined views as to the uniformity of nature would have been useful to the chicken.” Of course, geologists are well aware of this limitation. They know that the present physical conditions do not necessarily reflect the past physical conditions. For example, our geological findings show that the paleo-climate conditions of the Earth are not the same as our present climate conditions; in fact, it’s been evolving in deep time. Just like the atmosphere, the mineral world has also been evolving, creating new minerals from its predecessors. In general, a whole array of things was way different in the past and interacted differently. These facts but make us wonder whether the utility of uniformitarianism is diminishing.

At face value, it may look like the utility of uniformitarianism is on its last leg. Especially, with the emergence of numerical modeling, and advanced statistical tools including AI. It seems like simulation of the past conditions with a multiple-hypotheses approach may help us better understand the physio-chemical evolution of the Earth better. This is true and more reliant on deductive reasoning. Still, we need a reference for all kinds of numerical and deterministic computations. Uniformitarianism comes, yet again, as the key and not as the exact copy of the past. Secondly, regardless of the nature of reasoning employed, the concept of uniformitarianism should be honored to investigate Earth’s history. In other words, either the present physical processes or the law that governs the physical processes must be considered as immutable for geological investigations to be possible. Despite its limitations, uniformitarianism will continue to serve as one of the pillars of geology. It shall also remind earth scientists that they should always thrive to disprove their hypotheses and the ones they could not disprove, they should accept with a grain of salt.

– Luel, your friendly geologist