Rock & Mineral Encyclopedia

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

Arkose

A coarse, feldspar-rich sandstone, often pink, that records rapid erosion of granitic source rock under arid conditions.

A common coarse-grained intrusive rock like granite but richer in plagioclase than potassium feldspar.

An opaque brown chalcedony whose iron-stained banding mimics deserts, dunes, and distant mountain skylines.

Ancient chemically deposited rock of alternating iron-oxide and silica bands recording Earth's early oxygenation and a major iron ore source.

An altered granite of pink feldspar, green epidote and quartz, mottled pink-and-green and popular as a tumbled and carving stone.

A pegmatite rock of feldspar intergrown with wedge-shaped quartz that resembles ancient runic or Hebrew writing.

A banded, metamorphosed iron formation in which bright red jasper alternates with silvery hematite or magnetite layers.

An altered granite mottled pink and green from feldspar and epidote, popular as a tough, colorful ornamental rock.

Agate that forms in flat cracks or veins of host rock rather than rounded nodules, producing straight, parallel banding.

A coarse-grained intrusive igneous rock dominated by alkali feldspar with little or no quartz.

A schist derived from clay-rich sediments, rich in mica and often bearing index minerals like garnet, staurolite, or kyanite.

A fine-grained, sodium-rich contact-metasomatic rock formed where shale is albitized next to intruding diabase or spilite.

A green-and-red ornamental stone of epidote and red piemontite or iron oxide, named for its dragon-skin coloring; not a true jasper.

An Australian green rhyolite with eye-like orbs and earthy patterns marketed as jasper, evoking dense rainforest foliage.