Rock & Mineral Encyclopedia

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

Boulder Opal

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

A pale, silvery schist dominated by paragonite, the sodium-rich white mica, formed in aluminous metamorphic rocks.

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