Rock & Mineral Encyclopedia

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

Owyhee Blue Agate

A soft sky-blue chalcedony from the Owyhee region of Oregon and Idaho, prized for its calming, opaque powder-blue color.

A banded combination rock of golden tiger's eye, red jasper, and metallic hematite, formed in ancient iron deposits.

A richly colored red banded agate prized by lapidaries for its deep crimson-to-brown tones reminiscent of pigeon's blood.

A rare calcium-rich lithium tourmaline famous for the spectacular concentric color zoning seen in polished cross-section slices.

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

Tabular quartz crossed by a milky white thread-like line marking where the crystal repeatedly cracked and re-healed.

Black volcanic glass crossed by a fine network of grey or brown veins that resemble a spider's web.