Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Siberite
A historic name for the red-violet to purplish lithium tourmaline first prized from Siberia, closely tied to the rubellite variety.
gemstone
Black Obsidian
Jet-black natural volcanic glass formed by rapidly cooled lava, prized for its glassy luster and razor-sharp conchoidal fracture.
igneous
Aquamarine
The serene blue-to-sea-green variety of beryl, aquamarine is a durable gemstone colored by trace iron and birthstone for March.
gemstoneOrca Agate
A bold black-and-white banded chalcedony named for its orca-like coloring, popular as carvings and statement jewelry.
gemstoneCarrara Marble
A famous white to blue-grey Italian marble from Carrara, prized for centuries by sculptors and architects for its purity and fine grain.
metamorphic
Rosolite Garnet
A rose-pink variety of grossular garnet from Mexico, also known as landerite or xalostocite, prized for its soft pink color.
gemstone
Peacock Ore
A copper-iron sulfide ore famous for its iridescent peacock-like purple and blue tarnish; often sold as treated chalcopyrite.
mineral
Granite
A coarse-grained, speckled intrusive rock built from quartz, feldspar, and mica, forming the bedrock of the continents.
igneous
Verdelite
The classic green gem variety of elbaite tourmaline, ranging from bright grass-green to deep forest tones colored by iron or chromium.
gemstone
Silcrete
Extremely hard surface rock formed when silica cements soil and sediment into a tough duricrust in arid landscapes.
sedimentary
Owyhee Jasper
A picture jasper from the Owyhee region of Oregon and Idaho, prized for scenic tan, cream, and blue-grey landscape patterns.
mineral
Mariposite
A green, gold-associated metamorphic rock made of chrome-rich mica and quartz, named for Mariposa County in California's gold country.
metamorphic
Sideromelane
A transparent, pale brown basaltic volcanic glass formed when basalt lava is quenched extremely fast, often underwater.
igneous
Carnelian
A warm orange-to-red variety of chalcedony quartz colored by iron oxide, used since antiquity for seals, beads, and cabochons.
gemstone
Pink Garnet
A trade name for pink garnets, mainly rhodolite, a rose-to-purplish pyrope-almandine blend prized for its bright clean color.
gemstone
Biotite Schist
A foliated metamorphic rock dominated by glittering dark biotite mica, formed from mudstones under medium-grade regional metamorphism.
metamorphic
Rhodolite Garnet
A purplish-red to raspberry garnet that is a natural blend of pyrope and almandine, prized for its bright rose-violet color.
gemstone
Lignite
The lowest rank of coal, a soft brown carbon-rich rock formed from compacted peat, used mainly for electricity generation.
sedimentaryBlack Onyx
A solid jet-black chalcedony, usually a dyed and treated agate, prized for sleek polished beads, cabochons, and intaglios.
gemstone
Queensland Agate
Banded agate from Queensland, Australia, including the famous Agate Creek field, known for vivid fortification patterns.
gemstone
Zincite
A rare zinc oxide best known for its deep red to orange color, classically from Franklin, New Jersey, and as colorful man-made crystals.
mineral
Goldmanite
A green, vanadium-dominant garnet that forms in vanadium-rich metamorphic and sedimentary rocks, notably in uranium-vanadium districts.
mineral
Green Garnet
An umbrella term for green members of the garnet group, including prized tsavorite, demantoid, and rare chrome-rich uvarovite.
gemstone
Obsidian
A glassy, jet-black volcanic rock formed when lava cools too fast to crystallize, prized for razor-sharp conchoidal edges.
igneous