Rock & Mineral Encyclopedia

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

Oolite

A limestone made of tiny spherical ooids, resembling fish roe, formed in warm, agitated shallow seas.

Limestone built from tiny rounded ooid grains resembling fish roe, formed in warm, agitated shallow seas.

Sand-grained limestone composed of carbonate particles such as shell fragments and ooids cemented into a calcite rock.