Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Danburite

A glassy calcium borosilicate forming wedge-tipped prismatic crystals, usually colorless to pale yellow or pink, sometimes faceted as a gem.

Black volcanic glass marked with rounded spots and patches that resemble a leopard's coat, caused by spherulitic crystallization.