Rock & Mineral Encyclopedia

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

Kambaba Jasper

A dark green-and-black stromatolite jasper patterned with swirling orbs, formed from fossilized ancient microbial colonies.

Dark, organic-rich fine-grained sedimentary rock formed in oxygen-poor waters, often a source rock for oil and gas.

A fine-grained sedimentary rock rich in solid organic matter (kerogen) that yields oil and gas when heated.

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

A soft sedimentary evaporite made of massive gypsum, deposited when sulfate-rich seawater or lake water evaporates and concentrates.

Ilmenite is the world's leading source of titanium, a heavy iron-black oxide common in mafic rocks and black sands.

An agate whose layered, segmented banding resembles the jointed stalks and leaves of bamboo.