Rock & Mineral Encyclopedia

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

Acanthite

A silver sulfide that is one of the most important silver ore minerals, forming dark metallic crystals and wires.

A soft pink to crimson hydrated cobalt arsenate, famous as cobalt bloom that signals nearby cobalt ores.

A pale copper-red nickel arsenide, historically called kupfernickel, that is an ore of nickel and gives the metal its name.