Rock & Mineral Encyclopedia

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

Chalcocite

A dark gray copper sulfide that is one of the richest copper ores, prized by collectors when found as rare sharp crystals.

A brassy copper-iron sulfide that is the world's most important copper ore, often showing colorful iridescent tarnish.

Cuprite is a deep red copper oxide and an important secondary copper ore, prized for its rare ruby-red gem crystals.

Black volcanic glass with a warm bronze or coppery sheen produced by light reflecting off aligned microscopic inclusions.

A copper iron sulfide famous for its vivid iridescent purple-blue tarnish, the classic peacock ore and a copper ore.

A gray copper-antimony sulfosalt of the fahlore group, an important ore of copper and often silver, forming tetrahedral crystals.

A distinctive tourmaline-rich granite from Cornwall, prized as an ornamental stone for its pink feldspar set with radiating black tourmaline.

A water-bearing massive grossular garnet, usually green or pink, widely used as a tough jade-like carving stone.

A green ornamental stone, often serpentine-rich marble or verde antique, valued for its rich green color and white veining.

A soft mint-green variety of common opal, usually opaque and colored by trace copper or nontronite inclusions rather than play-of-color.

Australia's classic light-bodied precious opal from Coober Pedy, famed for milky white stones flashing pastel rainbow play-of-color.