Rock & Mineral Encyclopedia

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

Peruvian Pink Opal

A soft pink common opal from the Peruvian Andes, prized for its opaque rosy color rather than play-of-color.

The blue color variety of beryl, ranging from pale sky tones to rich sea-blue, best known in its finest grades as aquamarine.

A limestone made of tiny spherical ooids, resembling fish roe, formed in warm, agitated shallow seas.

A naturally magnetized variety of magnetite that attracts iron, historically used as the first magnetic compass.

A rare iron-rich (ferric) species of the tourmaline group, dark brown to bronze-black, named after crystallographer Martin Buerger.