Fuchsite | Chromium Rich Muscovite
The mineral fuchsite is a variety of chromium rich muscovite which is the cause of the mineral's rich green colour. The more chromium that's present the stronger the colour and in some cases it can even be similar to emerald. When replaced by aluminium the shade of green becomes distinctively lighter.
Fuchsite which is a radioactive mineral fluoresces lime green under ultraviolet light due to the presence of potassium. It can often be found as tiny mineral inclusions within certain rocks but when present in larger quantities it becomes known as verdite. Verdite is used primarily for decorative purposes.
Fuchsite is a relatively soft mineral that's rarely found with good purity. It grades 2 to 3 on Mohs scale of mineral hardness and often features inclusions of red corundum. Ruby in fuchsite as it's correctly known is often mistaken for ruby zoisite which is much rarer and considerably more expensive. Ruby zoisite is also harder than ruby in fuchsite and more often than not will also exhibit visible crystals of black hornblende.
The name fuchsite is often misspelt and mispronounced. The mineral was named after the German chemist and mineralogist Johann Nepomuk von Fuchs hence the correct pronunciation is fook-site.
The fuchsite mineral in our photo is on display in the Natural History Museum London. Photo by Stone Mania ©. The photo in its original size can be seen by clicking the image.