Rock & Mineral Encyclopedia

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

Red Agate

A red-toned banded chalcedony colored by iron oxides, ranging from natural carnelian-like reds to heat-treated stones.

A solid jet-black chalcedony, usually a dyed and treated agate, prized for sleek polished beads, cabochons, and intaglios.

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

A treated chalcedony with a network of crackled veins, usually heated and dyed in vivid colors for affordable, eye-catching beads.

A translucent chalcedony agate containing delicate, feather- or plume-shaped mineral inclusions that branch like soft feathers.

A nodular rhyolite geode-like ball whose plain exterior hides a star-shaped agate or chalcedony core when cut.

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

A soft sky-blue banded chalcedony prized for its delicate, lace-like white and blue swirling patterns.