Rock & Mineral Encyclopedia

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

Conglomerate

A coarse sedimentary rock of rounded pebbles and gravel cemented in a finer matrix, recording ancient rivers and beaches.

A rounded sedimentary nodule cracked internally and filled with veins of yellow calcite, prized for its striking dragon-skin patterning.

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

An iron-rich sedimentary rock, often heavy and rusty-weathering, historically mined as a major source of iron ore.