Rock & Mineral Encyclopedia

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

Smoky Obsidian

Translucent smoky-gray obsidian that transmits a hazy light, intermediate between clear and fully black volcanic glass.

A black volcanic glass with a soft, velvety internal sheen caused by aligned microscopic inclusions catching the light.

Black volcanic glass that reveals a soft purple-to-violet sheen at certain angles, caused by light interference off aligned inclusions.

Black volcanic glass with a warm bronze or coppery sheen produced by light reflecting off aligned microscopic inclusions.

Opal with a dark grey body tone sitting between black and light opal, giving play-of-color rich contrast at an accessible price.

Black volcanic glass that flashes a green sheen at certain angles due to light interference off aligned microscopic inclusions.

Black volcanic glass displaying a silvery shimmer from light reflecting off aligned microscopic gas bubbles trapped in the obsidian.

Chromite is the only commercial ore of chromium, a black iron-chromium oxide of the spinel group found in mafic igneous rocks.

A black-and-white striped chalcedony-quartz rock whose bold zebra-like banding makes it a popular ornamental and lapidary stone.

Ilmenite is the world's leading source of titanium, a heavy iron-black oxide common in mafic rocks and black sands.

A hard zinc-rich member of the spinel group, usually dark blue-green to black, forming octahedral crystals in metamorphic and pegmatitic rocks.

A sought-after elbaite tourmaline in teal hues that blend blue and green, prized for its ocean-like color.

A rare tourmaline showing a fixed wheel-like pattern of color zones and arms radiating from the crystal's center.

A warm cognac-brown to reddish-brown tourmaline, typically magnesium-rich dravite, prized for its rich whisky-like color.

Black volcanic glass laced with delicate web-like veins of contrasting color, formed by flow banding and fine crystallization.