Rock & Mineral Encyclopedia

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

Aurora Obsidian

A trade name for rainbow-sheen obsidian whose aligned nanoparticles produce shifting aurora-like bands of color.

A rare breccia formed by meteorite impact, containing shocked rock fragments and glassy melt blobs welded together.

A dark, glassy rock formed when frictional heat from fault movement or impact melts rock along narrow veins.

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

Obsidian containing spherulites — small radiating spheres of feldspar and cristobalite that crystallized within the cooling volcanic glass.

A clear, soft crystalline variety of gypsum that forms glassy or fibrous wands, so soft it can be scratched with a fingernail.

A glassy calcium borosilicate forming wedge-tipped prismatic crystals, usually colorless to pale yellow or pink, sometimes faceted as a gem.

An opaque, iron-rich basaltic volcanic glass formed by the rapid chilling of basalt lava, darker and denser than rhyolitic obsidian.

Jelly Garnet is a translucent grossular garnet whose soft, glassy, gummy-looking body gives it a jelly-like appearance.

Fine, golden, hair-like strands of basaltic volcanic glass spun from fluid lava droplets during eruptions, named for the Hawaiian volcano goddess.