Rock & Mineral Encyclopedia

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

Cassiterite

Tin oxide and the principal ore of tin, a dense, hard mineral mined since the Bronze Age for tin metal.

A metallic cobalt-nickel arsenide, an important cobalt ore, named for the Skutterud mines of Norway.

A feldspar gemstone that sparkles with metallic glints (aventurescence) caused by tiny reflective copper or hematite platelets.