Rock & Mineral Encyclopedia

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

Tiger's Eye

A golden-brown chatoyant quartz with a shimmering silky band of light, formed when quartz replaces fibrous crocidolite.

The blue-grey relative of tiger's eye, a chatoyant quartz showing a shifting band of light like a bird of prey's eye.

A chalcedony agate marked by round, concentric ring patterns that resemble eyes when cut and polished.

Aquamarine that shows a bright moving band of light, or cat's eye, caused by parallel needle-like inclusions when cut as a cabochon.

A banded combination rock of golden tiger's eye, red jasper, and metallic hematite, formed in ancient iron deposits.

A translucent common opal from the Andes prized for its serene blue to blue-green color, usually cut into cabochons and beads.

A brecciated, chatoyant quartz with swirling blue, gold, and brown fibers that shimmer like a stormy sky.

A Norwegian intrusive rock whose feldspar crystals flash silvery-blue, widely used as blue pearl granite countertops.

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

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