Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Peristerite
A sodium-rich plagioclase moonstone whose fine intergrowth lamellae scatter light into a delicate blue, pigeon-neck sheen.
gemstone
Oregon Sunstone
A copper-bearing labradorite feldspar from Oregon, famous for its range of natural colors and glittery aventurescent copper schiller.
gemstone
Greywacke
A hard, dark, poorly sorted sandstone with a muddy matrix, typically deposited by underwater turbidity currents.
sedimentaryRainbow Moonstone
A near-colorless feldspar showing blue and multicolored sheen; gemologically a white labradorite rather than true orthoclase moonstone.
gemstoneParticolored Tourmaline
A tourmaline displaying two or more distinct colors in a single crystal, prized for natural color zoning like watermelon and bicolor stones.
gemstoneStar Moonstone
A rare moonstone that shows a four-rayed star of light (asterism) across its domed surface along with adularescence.
gemstone
Yellow Labradorite
A transparent yellow to golden gem variety of labradorite feldspar, usually faceted to show its clear, warm color.
gemstone
Bostonite
A fine-grained, feldspar-rich dike rock with a trachytic texture, essentially a hypabyssal equivalent of trachyte or syenite.
igneous
Limburgite
A dark, glass-rich volcanic rock of olivine and augite phenocrysts set in a feldspar-free glassy groundmass, named from the Kaiserstuhl region.
igneous
Feldspathic Sandstone
A feldspar-rich sandstone, often pink, that points to granitic source rocks eroded quickly in dry or cold climates.
sedimentaryTri-Color Tourmaline
Tourmaline displaying three distinct color zones in a single crystal, a striking natural result of changing growth chemistry.
gemstone
Bi-Color Tourmaline
Tourmaline displaying two distinct colors in a single crystal, a natural color-zoning effect that makes each stone unique.
gemstone
Color Change Garnet
A rare garnet that dramatically shifts color from greenish in daylight to reddish under lamplight, rivaling alexandrite.
gemstone
Bi-color Beryl
A single beryl crystal showing two distinct color zones, such as aquamarine blue grading into morganite pink, within one stone.
gemstone
Color-Change Tourmaline
A rare tourmaline that visibly changes color between daylight and incandescent light, similar to the alexandrite effect.
gemstoneUnakite Jasper
An altered granite of pink feldspar, green epidote and quartz, mottled pink-and-green and popular as a tumbled and carving stone.
metamorphic
Moonstone
A feldspar gem famous for adularescence, a floating blue-white glow that shimmers across the stone like moonlight.
gemstone
Syenite
A coarse-grained intrusive igneous rock dominated by alkali feldspar with little or no quartz.
igneous
Cleavelandite
A striking platy, blade-like variety of albite feldspar that grows in fanned aggregates of thin white crystals within granite pegmatites.
mineral
Arkose
A coarse, feldspar-rich sandstone, often pink, that records rapid erosion of granitic source rock under arid conditions.
sedimentary
Belomorite
A regional Russian name for a moonstone-like plagioclase from the White Sea coast, prized for its bluish, slightly iridescent schiller.
gemstone
Unakite
An altered granite mottled pink and green from feldspar and epidote, popular as a tough, colorful ornamental rock.
metamorphicMulticolor Tourmaline
Tourmaline crystals displaying two or more distinct colors at once, including the famous pink-and-green watermelon variety.
gemstone
Green Moonstone
A pale green variety of feldspar moonstone showing a soft white or bluish adularescent sheen over a greenish body.
gemstone