Pyrophyllite - Al₂Si₄O₁₀(OH)₂

Habit: White, gray, pale blue, pale green, pale yellow or brownish green. Compact spherulitic aggregates of needle­like radiating crystals, fine-grained foliated laminae, granular or massive. Pearly to dull luster; translucent to opaque. White streak.

Environment: Somewhat uncommon, found both in hydrothermal veins and in bedded deposits in schistose metamorphic rocks.

Etymology: From the Greek words for "fire" and "leaf," for the way it exfoliates when heated.