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

A banded variety of chalcedony quartz, classically black or black-and-white, long favored for cameos and beads.

A fine-grained, sodium-rich contact-metasomatic rock formed where shale is albitized next to intruding diabase or spilite.

A chalcedony agate with red, orange, and yellow plume or banding patterns that rise like dancing flames within the stone.

Tabular quartz crossed by a milky white thread-like line marking where the crystal repeatedly cracked and re-healed.

Clear quartz crystals marked by distinctive horizontal ladder-like striations, popularized from Brazil as a metaphysical stone.

A general term for light-colored, fine-grained volcanic rocks rich in quartz and feldspar, like rhyolite.

A pink, manganese-rich variety of zoisite used as an ornamental gemstone, often mottled with white quartz and grey matrix.