Rock & Mineral Encyclopedia

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

Onyx Marble

Translucent banded calcium-carbonate stone deposited in caves and springs, prized for ornamental carvings despite its softness.

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

A banded, porous limestone deposited by mineral springs, prized as a warm-toned natural building and tile stone.

A banded chalcedony with straight, ribbon-like parallel layers, often cut across the bands for striking striped cabochons.

A deep black variety of banded chalcedony, often closely related to or treated like onyx, used for jewelry and carvings.

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

A copper-iron sulfide ore famous for its iridescent peacock-like purple and blue tarnish; often sold as treated chalcopyrite.

A soft, fine-grained, translucent form of gypsum (or banded calcite) long prized as a carving and ornamental stone.

A man-made opalescent glass that glows milky blue in reflected light and warm orange when backlit, often sold as a crystal.