Rock & Mineral Encyclopedia

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

Diamond

The hardest known natural material, a crystalline form of pure carbon prized as the ultimate gemstone for its brilliance and fire.

A brilliant green grossular garnet colored by chromium and vanadium, rivaling emerald with superior brilliance and durability.

A glacier-transported banded agate from the Lake Superior region, colored by iron into rich reds and oranges, and Minnesota's state gemstone.

The rarer and more valuable of the two jade minerals, prized for its translucent emerald-green 'imperial' color and extreme toughness.

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

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.