Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Limestone
A soft carbonate sedimentary rock made mostly of calcite, often packed with marine fossils and prone to forming caves.
sedimentary
Chrysocolla
A vivid blue-green hydrated copper silicate, soft on its own but prized as a gem when hardened by intergrown quartz or chalcedony.
mineral
Onyx
A banded variety of chalcedony quartz, classically black or black-and-white, long favored for cameos and beads.
gemstone
Calc-schist
A foliated metamorphic rock of calcite mixed with mica, quartz, and calc-silicate minerals, derived from marly sediments.
metamorphicOutlaw Jasper
A boldly patterned western jasper in browns, reds, and golds, prized by lapidaries for its dramatic scenic and brecciated figures.
gemstoneWoodbine Jasper
An earthy-toned jasper with vine-like or scenic patterning, valued by lapidaries for warm browns, reds, and creams that polish to a smooth finish.
gemstone
Lotus Jasper
A softly patterned jasper in cream, gray, and tan whose markings can suggest lotus petals, popular for calm, neutral-toned jewelry.
gemstone
Scheelite
Scheelite is a calcium tungstate ore of tungsten, famous for its brilliant blue-white fluorescence under ultraviolet light.
mineralBamboo Agate
An agate whose layered, segmented banding resembles the jointed stalks and leaves of bamboo.
gemstoneSpiderweb Jasper
A jasper crossed by fine dark veins forming a spiderweb-like network, often a brecciated stone cemented by darker matrix.
mineralSesame Jasper
A finely speckled pale jasper trade stone named for its sesame-seed-like flecks, closely related to Kiwi Jasper.
mineralLizard Skin Jasper
A patterned jasper whose scaly, net-like markings recall reptile skin, popular with lapidaries for its organic camouflage look.
gemstoneButterstone Jasper
A soft-toned cream-to-butterscotch jasper colored by iron oxides, prized by lapidaries for its smooth, even, opaque finish.
gemstoneFrog Skin Jasper
A mottled green jasper whose blotchy spotting resembles frog skin, valued by lapidaries for its earthy, camouflage-like patterns.
gemstoneOwyhee Blue Jasper
A soft blue-gray jasper from the Owyhee region of Oregon and Idaho, prized for its rare, calming blue tones among earthy jaspers.
gemstone
Dalmatian Jasper
A cream-colored spotted stone resembling a Dalmatian dog, made of feldspar and quartz dotted with dark mineral grains.
igneous
Siltstone
A fine-grained clastic rock of silt-sized grains, intermediate between sandstone and mudstone, with a gritty feel.
sedimentary
Tree Agate
A white chalcedony filled with green or black dendritic, tree-like mineral inclusions that resemble ferns or moss frozen in stone.
gemstoneExotica Jasper
Also called Sci-Fi Jasper, a Mexican jasper-rhyolite with swirling abstract patterns in cream, tan, gray, pink, and green.
gemstoneCobra Jasper
A banded jasper with cream, tan, and brown layers resembling snakeskin, often sourced from Madagascar.
mineral
Black Jasper
A dense, opaque black variety of microcrystalline quartz historically used as a touchstone for testing precious metals.
mineralRainforest Jasper
An Australian green rhyolite with eye-like orbs and earthy patterns marketed as jasper, evoking dense rainforest foliage.
igneous
Green Jasper
An opaque green variety of chalcedony quartz colored by iron and chlorite-group inclusions, prized as a durable carving and cabochon stone.
mineralCrowley Ridge Agate
Agate found in the gravels of Crowley's Ridge in northeastern Arkansas, a stream-transported banded chalcedony.
gemstone