Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Euxenite
A black rare-earth niobium-tantalum oxide, often radioactive and metamict, mined for yttrium, niobium, and associated rare elements.
mineral
Fancy Jasper
A soft-toned, multicolored jasper with swirling green, mauve, and cream patterns, popular and affordable in the bead trade.
sedimentary
Gabbro
A coarse-grained, dark mafic intrusive rock that is the plutonic equivalent of basalt, rich in plagioclase and pyroxene.
igneous
Flint
A hard, dark variety of chert that knaps into razor-sharp edges and sparks against steel, central to Stone Age technology.
sedimentary
Covellite
A soft copper sulfide famous for its intense indigo-blue color and dazzling iridescent metallic sheen, prized by collectors.
mineral
Electric Blue Obsidian
Obsidian with a vivid blue sheen or hue; natural blue obsidian is rare, and intensely uniform blue material is usually manufactured glass.
igneous
Deschutes Jasper
A prized Oregon picture jasper from the Deschutes region known for soft scenic landscapes in cream, tan, and blue-gray.
mineral
Claystone
A very fine-grained sedimentary rock made mostly of clay minerals, smooth to the touch and lacking the gritty feel of siltstone.
sedimentary
Clear Beryl
Transparent, colorless beryl (goshenite), the pure form of the species valued for its clarity, hardness, and well-formed crystals.
gemstone
Chrome Tourmaline
An intensely green tourmaline colored by chromium and vanadium, prized for its vivid emerald-like color from East Africa.
gemstone
Chevron Amethyst
A naturally banded quartz combining purple amethyst and white quartz in striking V-shaped chevron or zigzag patterns.
crystal
Charnockite
A granite-like rock containing orthopyroxene, formed at high temperatures and pressures and often classed with the granulites.
igneous
Carey Plume Agate
A prized plume agate from near Carey, Idaho, showing red, pink and black feathery plumes floating in translucent chalcedony.
gemstone
Carrara 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
Carver Agate
A collectible Oregon plume and scenic agate with feathery red and gold inclusions suspended in translucent chalcedony.
gemstone
Bog Iron
A soft, porous iron ore of limonite and goethite that forms in wetlands and bogs, historically the first iron source for many cultures.
sedimentary
Blue Tourmaline
Tourmaline in blue tones, encompassing iron-colored indicolite and the rare neon copper-bearing Paraiba, among the scarcer tourmaline colors.
gemstone
Black Onyx
A solid jet-black chalcedony, usually a dyed and treated agate, prized for sleek polished beads, cabochons, and intaglios.
gemstone
Black Obsidian
Jet-black natural volcanic glass formed by rapidly cooled lava, prized for its glassy luster and razor-sharp conchoidal fracture.
igneous
Bituminous Shale
A dark, organic-rich shale loaded with kerogen and bitumen that can yield oil and gas, often finely laminated and combustible.
sedimentary
Apricot Agate
A soft peachy-orange variety of banded chalcedony, naturally iron-tinted or dyed, popular for warm-toned beads and jewelry.
gemstone
Apophyllite
A glassy, often colorless silicate that forms pyramid-tipped cubes and is famed for its pearly basal cleavage and watery clarity.
crystal
Aquamarine
The serene blue-to-sea-green variety of beryl, aquamarine is a durable gemstone colored by trace iron and birthstone for March.
gemstone
Autumn Jasper
A warm-toned jasper named for its autumn-leaf palette of browns, rust, gold, and cream, popular as soothing earth-tone beads.
mineral