fuksit

Fuksit, commonly spelled fuchsite in English, refers to the chromium-rich green variety of muscovite, a mica in the phyllosilicate group. It is valued as a mineral specimen for its vivid emerald-green color and is encountered in metamorphic rocks as well as in some pegmatites.

In composition, fuchsite is a chromium-bearing form of muscovite. The typical muscovite formula is KAl2(AlSi3O10)(OH)2, and in fuchsite a portion of aluminum in octahedral sites is substituted by chromium, giving a formula that can be written as K(Al,Cr)2(AlSi3O10)(OH)2. This Cr substitution is responsible for the characteristic green hue. Fuchsite crystals are sheet silicates that crystallize in the monoclinic system, usually forming thin, plate-like leaves with perfect basal cleavage. The hardness is around 2 to 3 on the Mohs scale, and luster ranges from vitreous to silky.

Occurrence and formation typically involve metamorphic environments where chromium is available. It is commonly associated with other micas, chlorite, quartz, garnet, and tourmaline. Worldwide occurrences have been reported, with notable sources in India, Russia, Brazil, and parts of Africa. While aesthetically attractive, fuchsite is not a major chromium ore; its primary value lies in mineral collection, educational use, and occasional lapidary applications for specialty pieces. The spelling fuksit appears in some languages as an alternate transliteration of fuchsite.