Augelite - Al₂PO₄(OH)₃

Habit: Colorless to white; may be yellowish or pale rose. Thick tabular, prismatic to acicular crystals or thin triangular plates; also massive. Vitreous to pearly luster on cleavage planes; transparent. White streak.

Environment: Formed by hydrogen metamorphism of phosphate-bearing rocks in aluminum-rich sediments. Also occurs in some high-temperature hydrothermal ore deposits.

Etymology: From the Greek word for "luster," for its pearly luster on cleavage planes.