Rock & Mineral Encyclopedia

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

Olive Tourmaline

An earthy olive to yellowish-green tourmaline, a muted green-brown gem variety colored by iron with subtle warm undertones.

A soft mint-to-apple-green variety of calcite, a common calcium carbonate mineral popular as soothing tumbled stones.

A clastic sedimentary rock made of cemented sand grains, often quartz, recording ancient beaches, deserts, and rivers.

An affordable multicolored banded and mossy chalcedony from India, common in tumbled stones, beads, and meditation pieces.

A soft, glowing orange variety of calcite colored by iron oxides, popular as tumbled stones and known for fizzing in acid.

A soft, soothing powder-blue variety of calcite, a common calcium carbonate mineral often sold as gentle tumbled stones.

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

Ancient chemically deposited rock of alternating iron-oxide and silica bands recording Earth's early oxygenation and a major iron ore source.

A rare breccia formed by meteorite impact, containing shocked rock fragments and glassy melt blobs welded together.

A limestone packed with visible shells and shell fragments, recording the accumulation of marine invertebrate remains on ancient sea floors.

A cohesive fault rock formed by brittle crushing and grinding of rock along a fault zone, with angular fragments in a fine matrix.