Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Crowley Ridge Agate
Agate found in the gravels of Crowley's Ridge in northeastern Arkansas, a stream-transported banded chalcedony.
gemstone
Yellow-Green Obsidian
A chartreuse yellow-green glass sold as obsidian; the bright color is manufactured and does not occur in natural volcanic glass.
igneous
Neon Green Tourmaline
An intensely glowing green tourmaline, often copper-bearing, whose electric, almost luminous color recalls paraiba tourmaline.
gemstoneGreen Sheen Obsidian
Black volcanic glass that flashes a green sheen at certain angles due to light interference off aligned microscopic inclusions.
igneousGary Green Jasper
An Oregon jasper, also called larsonite, of silicified fossil wood showing olive-green fields laced with black dendritic patterns.
mineral
Dark Green Tourmaline
Deeply saturated green tourmaline colored by iron, often so dark it appears nearly black until viewed in bright light.
gemstone
Forest Green Tourmaline
A deep, rich forest-green elbaite tourmaline (verdelite) colored mainly by iron, with strong pleochroism and excellent durability.
gemstone
Cat's Eye Green Tourmaline
Green tourmaline cut as a cabochon to show a sharp moving band of light (chatoyancy) caused by fine parallel inclusions.
gemstoneBlack Onyx
A solid jet-black chalcedony, usually a dyed and treated agate, prized for sleek polished beads, cabochons, and intaglios.
gemstone
Chrome Chalcedony
A vivid green chalcedony colored by chromium, often called mtorolite, resembling chrysoprase but owing its color to chromium rather than nickel.
gemstone
Bloodstone
A dark green chalcedony speckled with blood-red spots of iron oxide, traditionally known as heliotrope.
gemstonePink Obsidian
A pink to rose volcanic glass; some is natural iron-tinted obsidian while much sold commercially is color-treated glass.
igneousBlue Obsidian
Blue-colored volcanic glass; genuine natural blue obsidian is very rare, while much blue obsidian on the market is manufactured glass.
crystal
Yellow Obsidian
Yellow to golden volcanic glass; natural examples owe their color to iron, though much bright yellow obsidian on the market is manufactured glass.
igneous
Howlite
A white, porous borate mineral webbed with gray-black veins, widely dyed to imitate turquoise and other stones.
mineral
Carnelian
A warm orange-to-red variety of chalcedony quartz colored by iron oxide, used since antiquity for seals, beads, and cabochons.
gemstoneSea Sediment Jasper
A colorful trade-name material, often dyed and reconstituted, sold as jasper; vivid blues and greens are typically artificially enhanced.
mineral
Mint Tourmaline
A soft, pastel minty-green tourmaline prized for its fresh, light color, a delicate variety of green elbaite.
gemstoneMint Obsidian
A pale mint-green glass sold as obsidian; most uniform light-green material on the market is manufactured glass rather than natural volcanic obsidian.
igneous
Prasiolite
A pale green variety of quartz, usually created by heat-treating amethyst, often marketed as green amethyst.
gemstone
Olive Tourmaline
An earthy olive to yellowish-green tourmaline, a muted green-brown gem variety colored by iron with subtle warm undertones.
gemstoneMint Opal
A soft mint-green variety of common opal, usually opaque and colored by trace copper or nontronite inclusions rather than play-of-color.
gemstone
Tsavorite Garnet
A brilliant green grossular garnet colored by chromium and vanadium, rivaling emerald with superior brilliance and durability.
gemstonePrase
An old name for a dull leek-green variety of quartz or chalcedony colored by green mineral inclusions, historically called mother of emerald.
crystal