Rock & Mineral Encyclopedia

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

Velvet Opal

Opal with a soft, velvety surface sheen rather than sharp play-of-color, prized for its gentle glow.

Fossil material whose original substance has been replaced by opal, preserving ancient shapes in common or play-of-color opal.

A common opal colored green by nickel or chromium impurities, usually opaque and cut into cabochons and beads.

Opal mined in Nevada, famous for fiery black precious opal and opalized wood from the Virgin Valley district.

An opal with a deep red body color, often a variety of Mexican fire opal, prized for its warm, glowing intensity.

A soft blue common opal, famously from Peru, valued for its serene sky-to-teal color rather than play-of-color.

A patterned common opal with mottled, leopard-like spots and blotches, prized as an ornamental and cabochon stone.

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 rare opal pseudomorph from White Cliffs, Australia, formed as opal replaced clustered crystals into a pineapple-like shape.

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

A clear, glassy, botryoidal common opal famous for its intense green fluorescence under UV light, caused by trace uranium.

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

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

An opal cut to show chatoyancy, a sharp moving band of light like a cat's eye, usually in honey, green or yellow common opal.

A hard, fine-grained siliceous rock with a dull porcelain-like texture, intermediate between soft diatomite and dense chert.