Petalite - LiAlSi₄O₁₀

Habit: Colorless, white or gray; rarely reddish or greenish. Crystals tabular or elongated and some faces may be striated; commonly foliated cleavable or massive. Vitreous luster, but pearly on some faces; transparent to translucent. Colorless streak.

Environment: Found in granite pegmatites, locally constituting an ore of lithium.

Etymology: From the Greek word for "leaf," in allusion to its perfect basal cleavage.