Rock & Mineral Encyclopedia

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

Serpentine

A group of green magnesium silicate minerals with a smooth, waxy feel, often carved and sometimes sold as imitation jade.

A green, often mottled metamorphic rock formed by the hydration of mantle rocks, soft and waxy with a smooth, slippery feel.

A green ornamental stone, often serpentine-rich marble or verde antique, valued for its rich green color and white veining.

A hydrous aluminum garnet (hydrogrossular) intermediate between grossular and katoite, common in altered calcium-rich and serpentinized rocks.

A sedimentary rock built from pea-sized concentric spheres called pisoids, often carbonate but sometimes iron or aluminum-rich.

Clusters of tiny botryoidal chalcedony spheres resembling bunches of grapes, famously purple, found in Indonesia.

Obsidian containing spherulites — small radiating spheres of feldspar and cristobalite that crystallized within the cooling volcanic glass.

A rare granitic rock containing concentric, onion-like spheres called orbicules, prized as a striking ornamental stone.

A calcium titanium silicate, gem-known as sphene, famous for fiery dispersion that exceeds diamond and rich green-to-yellow colors.

A banded agate whose internal structures resemble cathedral spires, arches, or a city skyline of towers and pinnacles.

Quartz with a stepped, multi-pointed structure of parallel side crystals resembling the spires of a cathedral.