Rock & Mineral Encyclopedia

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

Coral Rock

A porous limestone built from the calcium carbonate skeletons of corals and reef organisms, the lithified remains of ancient or modern reefs.

A warm-hued tourmaline blending orange, pink and red tones reminiscent of a sunset sky.

A gentle peach-to-apricot opal, mostly common opal colored by trace iron, prized for its soft warm pastel body.

A warm orange-to-red variety of chalcedony quartz colored by iron oxide, used since antiquity for seals, beads, and cabochons.