Rock & Mineral Encyclopedia

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

Feruvite

A calcium- and ferrous-iron-rich tourmaline, the iron analogue of uvite, forming dark brown to black crystals in skarns and metamorphic rocks.

A natural sheen obsidian whose black glass displays a soft, velvety rainbow shimmer from aligned magnetite nanoparticles when polished and tilted.

Opal from Madagascar spanning colorful common opal and some precious opal, including pink, green and boulder-type material.

A group of green magnesium silicate minerals with a smooth, waxy feel, often carved and sometimes sold as imitation jade.

A calcium-magnesium tourmaline that forms in metamorphosed limestones, typically dark green to brown and often in well-formed crystals.

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

Tourmaline crystals displaying two or more distinct colors at once, including the famous pink-and-green watermelon variety.

A rare color-change chrysoberyl that appears green in daylight and red under incandescent light, sometimes called emerald by day, ruby by night.