Rock & Mineral Encyclopedia

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

Quartzite

An extremely hard metamorphic rock formed from sandstone, made of fused quartz grains that break across rather than between the grains.

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

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

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

A hard, tough metamorphic rock of fused quartz grains, formed by recrystallizing quartz sandstone under heat and pressure.

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

A warm mustard-to-ochre yellow jasper colored by iron, valued by lapidaries for its rich, earthy golden tone.

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

A general term for light-colored, fine-grained volcanic rocks rich in quartz and feldspar, like rhyolite.