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 Blue Opal

A translucent common opal from the Andes prized for its serene blue to blue-green color, usually cut into cabochons and beads.

An opaque to translucent milky-white common opal valued for its soft porcelain-like color rather than play-of-color.

A warm golden-to-amber opal ranging from translucent common opal to precious stones that flash play-of-color over a honey body.

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

A translucent red opal, closely related to Mexican fire opal, glowing with a warm cherry-red body color often free of play-of-color.

A smoky gray feldspar moonstone, often called new moon stone, showing a silvery-blue adularescent sheen over a translucent gray body.

Opal from Oregon, USA, ranging from translucent blue Owyhee opal to clear and fiery contra-luz precious opal from Opal Butte.

A chromium-rich magnesium garnet of the pyrope series that crystallizes in the deep mantle and is a valuable diamond indicator mineral.