Rock & Mineral Encyclopedia

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

Appinite

A group of coarse, water-rich plutonic rocks dominated by large hornblende crystals set in feldspar, intermediate between lamprophyre and diorite.

A banded, metamorphosed iron formation in which bright red jasper alternates with silvery hematite or magnetite layers.

A banded variety of chalcedony quartz, classically black or black-and-white, long favored for cameos and beads.

A rare platinum arsenide and the most important platinum-bearing mineral, forming bright metallic cubic crystals.

A banded variety of chalcedony quartz, famed for its colorful concentric layers and enormous range of patterns and colors.

Rutile is a major titanium ore and the famous golden needle inclusion that gives rutilated quartz its shimmering threads.

A rich green, fuchsite-rich metamorphic rock from southern Africa, prized as a carving and ornamental stone.

A vivid blue-green hydrated copper silicate, soft on its own but prized as a gem when hardened by intergrown quartz or chalcedony.

A dark, mineral-rich dike rock with abundant mica or amphibole phenocrysts set in a fine groundmass, often associated with gold and diamonds.

Tourmaline in blue tones, encompassing iron-colored indicolite and the rare neon copper-bearing Paraiba, among the scarcer tourmaline colors.

A trade name occasionally used for golden-yellow beryl (golden beryl or heliodor), the iron-colored yellow variety of the emerald mineral.

A green ornamental stone, often serpentine-rich marble or verde antique, valued for its rich green color and white veining.

An intensely green tourmaline colored by chromium and vanadium, prized for its vivid emerald-like color from East Africa.

A warm mustard to brownish-yellow tourmaline, colored by iron or manganese, sitting between yellow and brown dravite tones.

A water-bearing massive grossular garnet, usually green or pink, widely used as a tough jade-like carving stone.