Pyrophyllite

Pyrophyllite is a silicate of aluminum. The sample above left has the labeled composition AlSi₂O₅(OH). It is about 6x9 cm and is from Staley, North Carolina. The sample at right has the labeled composition Al₂Si₄O₁₀(OH)₂. It is about 14x8 cm and is from Indian Gulch, Mariposa County, California. These samples are displayed in the Smithsonian Museum of Natural History.