Rock & Mineral Encyclopedia

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

Tiger Iron

A banded combination rock of golden tiger's eye, red jasper, and metallic hematite, formed in ancient iron deposits.

A soft, green iron-potassium mica that forms in marine sediments and gives greensand its characteristic olive color.

A rare swirling lilac-to-violet silicate found only in Siberia, prized for its fibrous, chatoyant purple patterns.

A foliated metamorphic rock dominated by glittering dark biotite mica, formed from mudstones under medium-grade regional metamorphism.

A green, glauconite-rich marine sandstone that records slow deposition on continental shelves and is used as a soil amendment.

A soft lithium-bearing mica with a lilac to purple color and pearly, flaky sheen, an important ore of lithium.