Rock & Mineral Encyclopedia

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

Chert

A hard, fine-grained sedimentary silica rock that breaks with sharp conchoidal edges, prized by ancient toolmakers.

A rare, prized Oregon picture jasper known for blue-green orbs and scenic patterns, often called the king of jaspers.

An opaque grey-brown common opal forming nodules and concretions, historically called liver opal for its dull brownish color.

A vivid green chalcedony colored by chromium, often called mtorolite, resembling chrysoprase but owing its color to chromium rather than nickel.

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

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