Rock & Mineral Encyclopedia

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

Rainbow Obsidian

A black volcanic glass that reveals concentric rainbow bands of color when cut and polished against the light.

A spectacularly banded agpaitic nepheline syenite of alternating red eudialyte, black amphibole and white feldspar layers from Ilimaussaq, Greenland.

Black volcanic glass marked with rounded spots and patches that resemble a leopard's coat, caused by spherulitic crystallization.

A speckled green-and-black stone resembling kiwi fruit, technically a quartz-amazonite aggregate rather than true jasper.

An opaque jasper from the Cave Creek area of Arizona, prized for earthy mottled and banded patterns in warm desert tones.

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

A natural volcanic glass with rich brown and black mahogany-like swirls created by iron oxide inclusions.

Black volcanic glass with a warm bronze or coppery sheen produced by light reflecting off aligned microscopic inclusions.

A translucent, soft blue variety of microcrystalline quartz whose color comes from light scattering through its fine structure.

A banded jasper with cream, tan, and brown layers resembling snakeskin, often sourced from Madagascar.

A rare Australian jasper from the Pilbara with bold red, yellow, and black abstract patterns, prized by collectors.

A moonstone variety displaying a moving band of light (chatoyancy) across its surface in addition to the classic moonstone glow.

Obsidian colored brown by iron oxide inclusions, frequently banded or swirled with black as in mahogany obsidian.