Rock & Mineral Encyclopedia

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

Emerald

The green chromium- and vanadium-colored variety of beryl, one of the four classic precious gemstones renowned for its rich green color.

A plagioclase feldspar famous for labradorescence, a dramatic flash of iridescent blue, green, and gold across a dark gray stone.

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

A group of silicate gemstones best known for deep red but spanning nearly every color, including green tsavorite and orange spessartine.

Smithsonite is a zinc carbonate ore famous for glassy botryoidal crusts in blue-green, pink, and yellow hues.

A trade name for sheen obsidian whose swirling, patchy iridescence resembles galaxies and nebulae against deep black glass.

A natural sheen obsidian showing a warm gold shimmer plus peacock iridescence, caused by aligned nanoparticle layers within black glass.