Rock & Mineral Encyclopedia

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

White Opal

The most common precious opal, with a pale milky body that shows softer pastel flashes of play-of-color throughout.

Opal from Australia, the world's leading source of precious opal, ranging from white and crystal to prized black and boulder types.

A nodular rhyolite geode-like ball whose plain exterior hides a star-shaped agate or chalcedony core when cut.