Rock & Mineral Encyclopedia

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

Mylonite

A fine-grained, strongly foliated rock formed deep in fault zones where rocks flowed and ground down rather than fracturing.

A manganese aluminum garnet glowing in vivid orange to reddish-orange tones, with the finest called mandarin garnet.

A warm cognac-brown to reddish-brown tourmaline, typically magnesium-rich dravite, prized for its rich whisky-like color.

A soft, reddish native metal with excellent conductivity, mined for wiring, plumbing, and alloys like bronze and brass.

A reddish-brown rare-earth phosphate that is a primary ore of cerium, thorium and other rare-earth elements, often found in placer sands.

A rare garnet that dramatically shifts color from greenish in daylight to reddish under lamplight, rivaling alexandrite.

Agate that was shattered and naturally re-cemented by silica, creating a mosaic of angular fragments in a quartz matrix.

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