Rock & Mineral Encyclopedia

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

Sapphire

The gem variety of corundum in every color except red, most prized in velvety blue and exceptionally hard and durable.

The blue gem variety of corundum, prized for its rich color, extreme hardness, and brilliance second only to diamond.

A pink to rose volcanic glass; some is natural iron-tinted obsidian while much sold commercially is color-treated glass.

The red, chromium-colored variety of corundum, prized as one of the most valuable colored gemstones and second only to diamond in hardness.

A striking rock of green zoisite studded with red-pink ruby crystals and black hornblende, also called anyolite.

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

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

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

A warmly colored chalcedony agate with reds, oranges, golds, and pinks that blend like the glowing bands of a sunset sky.

A water-bearing massive grossular garnet, usually green or pink, widely used as a tough jade-like carving stone.

The red to raspberry-pink variety of tourmaline, prized for its vivid ruby-like color that holds under both daylight and artificial light.

Elbaite tourmaline in purplish-pink to magenta hues, colored by manganese, prized for its vivid orchid-like tones.

A creamy pink-and-white chalcedony from Madagascar containing flower-like plume inclusions that resemble blossoms suspended in stone.

A multicolored orbicular chalcedony from Madagascar famous for its circular eye-like orbs in greens, pinks, whites, and yellows.

A pink-to-red quartz colored by iron oxide inclusions that create a speckled, strawberry-like appearance within clear crystal.