Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Orbicular Granite
A rare granitic rock containing concentric, onion-like spheres called orbicules, prized as a striking ornamental stone.
igneous
Graphic Granite
A pegmatitic granite in which quartz and feldspar intergrow to resemble ancient runic or Hebrew script.
igneous
Orthoclase
A common rock-forming potassium feldspar, the Mohs hardness reference at 6, found in granites and used in ceramics and glassmaking.
mineral
Charnockite
A granite-like rock containing orthopyroxene, formed at high temperatures and pressures and often classed with the granulites.
igneousMatte Obsidian
Obsidian with a dull, non-reflective surface from natural weathering or deliberate sandblasting/etching, rather than a distinct type of volcanic glass.
igneous
Norite
A coarse-grained mafic plutonic rock similar to gabbro but with orthopyroxene as the dominant pyroxene instead of clinopyroxene.
igneousFrosted Obsidian
Natural obsidian with a frosted, matte surface produced by weathering, abrasion, or etching rather than a separate variety of glass.
igneous
Gneiss
A high-grade metamorphic rock defined by alternating light and dark mineral bands, formed under intense heat and pressure.
metamorphic
Albitite
A pale rock made almost entirely of the sodium feldspar albite, formed by sodic magmatism or sodium metasomatism.
igneousLuxullianite
A distinctive tourmaline-rich granite from Cornwall, prized as an ornamental stone for its pink feldspar set with radiating black tourmaline.
igneous
Graphic Feldspar
A pegmatite rock of feldspar intergrown with wedge-shaped quartz that resembles ancient runic or Hebrew writing.
igneous
Unakite
An altered granite mottled pink and green from feldspar and epidote, popular as a tough, colorful ornamental rock.
metamorphicUnakite Jasper
An altered granite of pink feldspar, green epidote and quartz, mottled pink-and-green and popular as a tumbled and carving stone.
metamorphic
Thunderegg Agate
A nodular rhyolite geode-like ball whose plain exterior hides a star-shaped agate or chalcedony core when cut.
gemstone
Garnierite
A vivid green hydrous nickel-magnesium silicate that is a major ore of nickel, mined from weathered ultramafic rocks.
mineralCat's Eye Opal
An opal cut to show chatoyancy, a sharp moving band of light like a cat's eye, usually in honey, green or yellow common opal.
gemstoneCat's Eye Aquamarine
Aquamarine that shows a bright moving band of light, or cat's eye, caused by parallel needle-like inclusions when cut as a cabochon.
gemstone
Eye Agate
A chalcedony agate marked by round, concentric ring patterns that resemble eyes when cut and polished.
gemstone
Wolframite
Wolframite is the historic principal ore of tungsten, a heavy black tungstate forming bladed crystals in granite veins.
mineral
Feldspar
The most abundant mineral group in Earth's crust, feldspars are aluminosilicates that form much of granite and many igneous rocks.
mineral
Breccia
A coarse rock of angular, sharp-edged fragments cemented in a matrix, marking nearby rockfall, faulting, or impact.
sedimentary
Granodiorite
A common coarse-grained intrusive rock like granite but richer in plagioclase than potassium feldspar.
igneous
Rhyolite
A fine-grained, silica-rich volcanic rock that is the extrusive equivalent of granite, often pale, banded, or flow-textured.
igneous
Green Opal
A common opal colored green by nickel or chromium impurities, usually opaque and cut into cabochons and beads.
gemstone