Rock & Mineral Encyclopedia

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

Mariposite

A green, gold-associated metamorphic rock made of chrome-rich mica and quartz, named for Mariposa County in California's gold country.

Precious opal that forms in thin veins within brown ironstone boulders, cut with the host rock left as a natural dark backing.

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

Clear or smoky quartz threaded with golden to reddish needles of rutile, also poetically called Venus hair stone.

A hard, dark, poorly sorted sandstone with a muddy matrix, typically deposited by underwater turbidity currents.

A metamorphic rock made chiefly of manganese-rich spessartine garnet and quartz, formed from ancient manganese-bearing sediments.

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

A banded combination rock of golden tiger's eye, red jasper, and metallic hematite, formed in ancient iron deposits.

An Oregon picture jasper from the Rogue River area showing earthy scenic patterns in tan, brown, gold, and cream.

A celebrated plume agate from the Oregon-Idaho border, known for dramatic black, gold, and red plumes in clear chalcedony.

A dark, mineral-rich dike rock with abundant mica or amphibole phenocrysts set in a fine groundmass, often associated with gold and diamonds.

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

Rutile is a major titanium ore and the famous golden needle inclusion that gives rutilated quartz its shimmering threads.