Scientific Name: Chromium-rich muscovite mica
Group: Silicates - phyllosilicates
Chemical composition: K(Cr,Al)2(AlSi3)O10(OH,F)2
Colors: Light to medium green, from chromium.
Formation: Monoclinic crystal, Curved aggregate form
Principal Sources: New Hampshire, USA; Canada.
Special Notes: Fuschite's intensity of color depends on its chromium concentration, which may be up to 25%. Muscovite is the most common mica, found in granites, pegmatites, gneisses, and schists, and as a contact metamorphic rock or as a secondary mineral resulting from the alteration of topaz, feldspar, kyanite, etc. In pegmatites, it is often found in immense sheets that are commercially valuable. Muscovite is in demand for the manufacture of fireproofing and insulating materials and to some extent as a lubricant.