Rock & Mineral Encyclopedia

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

Basalt

A fine-grained, dark volcanic rock that erupts as fluid lava and forms most of the ocean floor and many lava plateaus.

The most abundant basalt type on Earth, a silica-saturated subalkaline lava that forms ocean crust and flood basalts.

A dark, highly vesicular volcanic rock full of gas bubbles, denser than pumice, common as red or black lava rock.

Basalt that has been metamorphosed, developing new minerals like chlorite, actinolite, and epidote that give it a greenish color.

A heavy lead sulfate secondary mineral, often colorless to white with adamantine luster, formed by the oxidation of galena.

A South African quartz whose central crystal is coated in a cactus-like crust of tiny secondary points, also called spirit quartz.

A hydrous zinc silicate, often sky-blue, that is an ore of zinc and a collectible mineral forming botryoidal crusts and crystals.

A lead phosphate secondary mineral known for barrel-shaped green to yellow crystals formed in oxidized lead deposits.

A high-grade metamorphic rock formed in the deep, hot crust, marked by anhydrous minerals like pyroxene and garnet.

The most abundant mineral group in Earth's crust, feldspars are aluminosilicates that form much of granite and many igneous rocks.