Life in the USA is not normal. It feels pointless and trivial to be talking about small looks at the fascinating natural world when the country is being dismantled. But these posts will continue, as a statement of resistance. I hope you continue to enjoy and learn from them. Stand Up For Science!
Uvarovite is chromium garnet, calcium chromium silicate, Ca3Cr2(SiO4)3.
Chromium is a really strong coloring agent in minerals, and sometimes other green garnets that have traces of chromium are called uvarovite, but they’re really chrome-bearing grossular or chrome-bearing andradite (variety demantoid), where grossular and andradite are other members of the garnet group. This one at the top is true uvarovite, from the type locality, the Saranovskii Mine in Permskaya Oblast, Russia.
That’s in the Ural Mountains, which began to form about the same time as the last pulse of the Appalachians, Carboniferous to Permian time, about 300 million years ago, and continuing into the Mesozoic Era. The Urals represent the collisions among the Siberian Craton, the Kazakh Craton, and the Baltic (or East European) Craton. Baltica had already pretty much amalgamated with North America and Gondwana (Africa + South America and more), and the Ural Orogeny was more or less the final stage of the formation of the supercontinent of Pangea.
Here's an example of green garnet that’s actually chrome-bearing grossular, Ca3(Al,Cr)2(SiO4)3, from the Orford Nickel Mine in Quebec. Obviously, you can’t go simply by color to call something uvarovite.
The chromium to make these garnets in the Urals probably came from slices of oceanic crust (ophiolites) that got caught up in the continent-continent collisions. Similar rocks are found in California, another place where uvarovite is well known.
Uvarovite was named for Count Sergey Semeonovich Uvarov (1786-1855), Russian statesman and scholar, President of the Russian Academy of Sciences in St. Petersburg from 1818 to 1855.
The Avebury Mine near Zeehan, Tasmania, has green garnets that straddle the mid-point of the series andradite-uvarovite. You need to basically analyse each specimen to determine which is the dominant species 😆
One of the most beautiful mineral/gemstones. I did not know that other varieties could also be green; I will just keep thinking that the ring I bought my wife is true Uvarovite.