Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Poppy Jasper
An orbicular jasper with red and orange flower-like spots resembling poppies, famously from Morgan Hill, California.
mineral
Peacock Ore
A copper-iron sulfide ore famous for its iridescent peacock-like purple and blue tarnish; often sold as treated chalcopyrite.
mineral
Cherry Creek Jasper
A landscape-patterned Chinese jasper prized for warm cherry-red, cream, and green bands resembling painted scenery.
mineral
Desert Rose
A rosette-shaped cluster of bladed gypsum or barite crystals that traps sand, forming flower-like formations in arid deserts.
mineral
Garnierite
A vivid green hydrous nickel-magnesium silicate that is a major ore of nickel, mined from weathered ultramafic rocks.
mineral
Orange Garnet
A trade term for orange garnets, mainly manganese-rich spessartine and the brownish hessonite variety of grossular.
gemstone
Orange Calcite
A soft, glowing orange variety of calcite colored by iron oxides, popular as tumbled stones and known for fizzing in acid.
mineral
Orbicular Granite
A rare granitic rock containing concentric, onion-like spheres called orbicules, prized as a striking ornamental stone.
igneous
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
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
Limestone
A soft carbonate sedimentary rock made mostly of calcite, often packed with marine fossils and prone to forming caves.
sedimentary
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
Greensand
A green, glauconite-rich marine sandstone that records slow deposition on continental shelves and is used as a soil amendment.
sedimentary
Leopard Opal
A patterned common opal with mottled, leopard-like spots and blotches, prized as an ornamental and cabochon stone.
gemstoneMint Garnet
A delicate pastel-green grossular garnet, lighter than tsavorite, most famously from the Merelani Hills of Tanzania.
gemstone
Pyromorphite
A lead phosphate secondary mineral known for barrel-shaped green to yellow crystals formed in oxidized lead deposits.
mineral
Septarian Concretion
A rounded sedimentary nodule cracked internally and filled with veins of yellow calcite, prized for its striking dragon-skin patterning.
sedimentary
Novaculite
An extremely fine-grained, dense siliceous rock famous as Arkansas whetstone, prized for sharpening fine cutting tools.
sedimentaryFireworks Obsidian
Black volcanic glass dotted with radiating spherulite bursts that look like exploding fireworks frozen in the stone.
igneous
Flame Agate
A chalcedony agate with red, orange, and yellow plume or banding patterns that rise like dancing flames within the stone.
gemstone
Landscape Opal
A common opal containing dendritic or mossy mineral inclusions that form miniature landscape-like scenes inside the stone.
gemstone