Rock & Mineral Encyclopedia

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

Spiderweb Obsidian

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

A mottled, multicolored obsidian blending black, brown, grey, and tan patches like a calico cat's patchwork coat.

A magnesium carbonate mineral, usually chalky white with grey veining, widely dyed to imitate turquoise and other stones.

A man-made glittering glass packed with tiny copper crystals, traditionally reddish-brown but also made in blue and green.

A famous white to blue-grey Italian marble from Carrara, prized for centuries by sculptors and architects for its purity and fine grain.

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

A pink, manganese-rich variety of zoisite used as an ornamental gemstone, often mottled with white quartz and grey matrix.

Black volcanic glass studded with oval, peanut-shaped grey-white spherulites of radiating crystals frozen in the glass.

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 dark, foliated schist rich in graphite that leaves a grey-black mark and forms from metamorphosed carbon-rich sediments.

A heavy, lead-grey metallic mineral with perfect cubic cleavage, galena is the world's main ore of lead and often carries silver.

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.