Pyrophyllite

Pyrophyllite is a soft, white, brown, or greenish mineral that’s used in ceramics and other applications. It’s a phyllosilicate mineral composed of aluminum silicate hydroxide and has a similar structure to talc. It occurs in phyllite and schistose rocks, often associated with kyanite, of which it is an alteration product. It also occurs as hydrothermal deposits. Typical associated minerals include kyanite, andalusite, topaz, mica, and quartz.