Rock & Mineral Encyclopedia

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

Calcarenite

Sand-grained limestone composed of carbonate particles such as shell fragments and ooids cemented into a calcite rock.

A dark mica lamprophyre with biotite and augite phenocrysts in a plagioclase-dominated groundmass, the feldspar counterpart of minette.

A feldspar-rich sandstone, often pink, that points to granitic source rocks eroded quickly in dry or cold climates.

A soft blue-gray jasper from the Owyhee region of Oregon and Idaho, prized for its rare, calming blue tones among earthy jaspers.

A pale jasper crossed by distinctive blue-gray veins or lines, valued by lapidaries for its calm color contrast.

A softly patterned jasper in cream, gray, and tan whose markings can suggest lotus petals, popular for calm, neutral-toned jewelry.

A foliated metamorphic rock of calcite mixed with mica, quartz, and calc-silicate minerals, derived from marly sediments.