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.

A metamorphic rock of calcium-rich silicate minerals formed from impure limestone or dolomite altered by heat and fluids.

A tough, fine-grained contact-metamorphic rock containing cordierite, often spotted, formed by heat from nearby igneous intrusions.

A rare chlorine-bearing iron garnet-supergroup mineral, the ferric analogue of wadalite, formed in high-temperature combustion-metamorphic rocks.

A rare, dense iron-rich metamorphic rock composed of fayalite, iron pyroxene, and almandine garnet.

A high-grade metamorphic rock formed in the deep, hot crust, marked by anhydrous minerals like pyroxene and garnet.

A limestone packed with visible shells and shell fragments, recording the accumulation of marine invertebrate remains on ancient sea floors.

A rare breccia formed by meteorite impact, containing shocked rock fragments and glassy melt blobs welded together.

A high-grade metamorphic gneiss of garnet, sillimanite, quartz, and graphite, derived from ancient aluminous sediments.

A green, vanadium-dominant garnet that forms in vanadium-rich metamorphic and sedimentary rocks, notably in uranium-vanadium districts.

A rare zirconium-bearing garnet that crystallizes in carbonatites and alkaline rocks, first described from Magnet Cove, Arkansas.

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

A dark, foliated schist rich in needle-like hornblende crystals, formed by metamorphism of mafic igneous rocks.