Rock & Mineral Encyclopedia

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

Onyx

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

A pale green variety of feldspar moonstone showing a soft white or bluish adularescent sheen over a greenish body.

The yellow variety of beryl, also called heliodor or golden beryl, colored by iron and valued for its bright color and durability.

A gentle peachy-pink tourmaline blending soft pink and orange tones, a delicate pastel variety of elbaite.

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

A green variety of macrocrystalline quartz, usually the heat- or radiation-altered prasiolite, prized for its soft mint hue.

A richly saturated green variety of elbaite tourmaline whose color rivals emerald, colored by trace iron, chromium, or vanadium.

A deep black variety of banded chalcedony, often closely related to or treated like onyx, used for jewelry and carvings.

Natural obsidian with a frosted, matte surface produced by weathering, abrasion, or etching rather than a separate variety of glass.

The classic green gem variety of elbaite tourmaline, ranging from bright grass-green to deep forest tones colored by iron or chromium.

A soft mint-green variety of common opal, usually opaque and colored by trace copper or nontronite inclusions rather than play-of-color.

Tourmaline crystals displaying two or more distinct colors at once, including the famous pink-and-green watermelon variety.

An old name for a dull leek-green variety of quartz or chalcedony colored by green mineral inclusions, historically called mother of emerald.