Rock & Mineral Encyclopedia

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

Double Flow Obsidian

Obsidian formed from two merged lava flows, producing a stone with two distinct bands of sheen or color.

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

A rose-pink manganese silicate marbled with black veins, prized as a tough ornamental and occasionally faceted gemstone.

A banded chalcedony with straight, ribbon-like parallel layers, often cut across the bands for striking striped cabochons.

Beryl displaying chatoyancy, a bright moving band of light, caused by parallel tube-like inclusions when cut as a cabochon.

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

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 white chalcedony filled with green or black dendritic, tree-like mineral inclusions that resemble ferns or moss frozen in stone.

A soft sky-blue banded chalcedony prized for its delicate, lace-like white and blue swirling patterns.

Tourmaline displaying chatoyancy, a moving band of light caused by parallel tube-like inclusions, when cut as a cabochon.

A trade name for rainbow-sheen obsidian whose aligned nanoparticles produce shifting aurora-like bands of color.

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

A banded jasper showing parallel ribbon-like stripes of contrasting color formed by layered silica and mineral deposition.

An opal cut to show chatoyancy, a sharp moving band of light like a cat's eye, usually in honey, green or yellow common opal.