You’ve heard the slogan, “Diamonds are forever” and while that’s meant to be marketed toward the jewelry customers, it also excites scientists studying diamonds.
This is because unlike when you’re shopping for an engagement ring, imperfections in the diamond are of great interest to scientists.
Through analysis of a single tiny grain imperfection within a diamond, researchers discovered a brand new mineral never before seen. The findings, published in American Mineralogist, officially introduced the new mineral goldschmidtite ((K,REE,Sr)(Nb,Cr)O3).
The diamond is from South Africa, more specifically the Koffiefontein pipe that is known for producing world-class diamonds and operated by the international diamond behemoth De Beers.
Trapped within the diamond itself is a tiny spec, an inclusion that the diamond grew over and around, trapping it within the diamond’s strong crystal lattice about 105 miles below the surface of the Earth. Inclusions in diamonds are not entirely unusual but they are exciting because it gives a glimpse into the geochemistry of the surrounding molten rock as the diamond formed.
The new mineral goldschmidtite, a dark green spec the width of a human hair, has unusual chemical properties. Thankfully, it was trapped within the diamond itself which is strong and stable enough to last millions to billions of years. Hence, it is a perfect “vessel” for preserving rare and unique minerals.
The dominant elements that make up the mantle where this diamond formed are magnesium, iron, etc. However, this spec contains niobium, potassium and the very rare elements lanthanum and cerium. The fact that this mineral contains such a unique concoction of rare elements is intriguing. How was there enough concentration of these rare elements to form this unusual mineral?
The processes by which this mineral formed must have been unique and the available elements must have been unique.
The new mineral is named after Victor Moritz Goldschmidt, who lived in the late 19th century and early 20th century and was an early and famous mineralogist. He was a pioneer in researching the perovskite crystal chemistry, a similar crystal chemistry as found in this newly discovered mineral.
The first step of identification of the mineral is now complete and the next step will be to develop a model for how this unusual mineral formed in the depths below South Africa. Certainly, the team will be looking for more examples of goldschmidtite in the Koffiefontein pipe to see if there are chemical variations and more clues as to how this unique mineral formed.
This isn’t the first time researchers have found precious information locked in diamonds. Back in 2014, a research team published a Nature paper on their discovery of hydrous minerals locked within a diamond. This provided direct evidence that water is locked away in the deep mantle.