Rock & Mineral Encyclopedia

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

Onyx

A banded variety of chalcedony quartz, classically black or black-and-white, long favored for cameos and beads.

A dark green chalcedony speckled with blood-red spots of iron oxide, traditionally known as heliotrope.

A vivid Australian jasper-like silica stone in earthy reds, yellows, and purples, formed from silicified radiolarian sediment.

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

A black volcanic glass threaded with delicate grey, swirling lace-like bands of flow lines that show beautifully when polished.

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

A chalcedony agate filled with radiating needle-like mineral inclusions, prized for its starburst and spray patterns.

A chalcedony agate with soft, billowing cloud-like masses of gray and white suspended in a translucent body.

A translucent agate containing delicate three-dimensional feather- or plant-like plumes of mineral inclusions suspended in chalcedony.

Agate containing radiating sprays of mineral needles that fan out like bursting stars within the chalcedony.

A pale chalcedony agate with cloudy, frost-like white patterning suggesting frost on a window or icy crystalline textures.

A translucent chalcedony agate containing delicate, feather- or plume-shaped mineral inclusions that branch like soft feathers.

A nodular rhyolite geode-like ball whose plain exterior hides a star-shaped agate or chalcedony core when cut.

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