Rock & Mineral Encyclopedia

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

Pelitic Schist

A schist derived from clay-rich sediments, rich in mica and often bearing index minerals like garnet, staurolite, or kyanite.

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

A translucent chalcedony from Montana filled with black and red dendritic inclusions that look like moss, ferns, or scenic landscapes.

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

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.

Black volcanic glass that flashes flame-like bands of iridescent color when light strikes aligned nanoscale inclusions.

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.

Obsidian crossed by parallel flow bands of differing color, formed as layers of lava with slightly different compositions froze into glass.

A pale green variety of quartz, usually created by heat-treating amethyst, often marketed as green amethyst.

A banded, metamorphosed iron formation in which bright red jasper alternates with silvery hematite or magnetite layers.