Rock & Mineral Encyclopedia

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

Pineapple Opal

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

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

A common opal with branching, tree-like mineral inclusions that create natural fern, moss, or landscape patterns.

A transparent, colorless opal that looks like water or jelly, sometimes flashing subtle play-of-color from within.

A common opal containing moss- or fern-like mineral inclusions that resemble plants suspended in a pale silica body.

Opal showing a smooth, silky satin-like sheen across its surface, valued for a gentle, refined luster.

A common opal containing dendritic or mossy mineral inclusions that form miniature landscape-like scenes inside the stone.

A precious opal showing dominant peacock-like blue, green and teal play-of-color, often on Ethiopian material.

A translucent, gelatinous-looking opal whose transparency gives floating, glowing play-of-color a watery, jelly-like appearance.

An opaque, porcelain-white common opal prized for its milky, pearl-like appearance and high porosity, often carved or beaded.

A precious opal pattern made of tiny, densely packed pinpoint flashes of play-of-color, like sparkling speckles across the stone.

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