Rock & Mineral Encyclopedia

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

Turquoise

A prized blue to blue-green copper-aluminium phosphate, often veined with dark matrix, treasured for jewelry across many cultures.

A cream-colored spotted stone resembling a Dalmatian dog, made of feldspar and quartz dotted with dark mineral grains.

A cream-colored feldspar-and-quartz rock peppered with dark spots, named for its resemblance to a Dalmatian dog.

A naturally banded quartz combining purple amethyst and white quartz in striking V-shaped chevron or zigzag patterns.

An extremely common calcium carbonate mineral that comes in nearly every color and shows strong double refraction in clear crystals.

Abundant banded chalcedony from southern Brazil, the world's main source of agate slices and dyed agate products.

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

Black volcanic glass dotted with radiating spherulite bursts that look like exploding fireworks frozen in the stone.

Black volcanic glass dotted with small light-colored mineral specks resembling stars scattered across a night sky.

A pink-and-green bicolor glass sold as obsidian; the watermelon coloring is manufactured and does not occur in natural volcanic glass.

A chartreuse yellow-green glass sold as obsidian; the bright color is manufactured and does not occur in natural volcanic glass.

A deep cobalt-blue glass sold as obsidian; intense blue body color is manufactured, as natural obsidian does not form bright blue glass.