Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Black Tourmaline
The opaque black iron-rich variety of tourmaline (schorl), forming striated prismatic crystals popular as a protective grounding stone.
mineral
Verdite
A rich green, fuchsite-rich metamorphic rock from southern Africa, prized as a carving and ornamental stone.
metamorphic
Angelite
A soft pale-blue calcium sulfate, the anhydrous form of gypsum, prized as a gentle, calming tumbled stone.
mineral
Chocolate Garnet
A rich brown variety of andradite (or grossular-andradite) garnet, marketed for its warm chocolate color and notable brilliance.
gemstoneCanary Tourmaline
The vivid, pure yellow tourmaline marketed as canary, a rare manganese-rich variety from Zambia and Malawi.
gemstone
Black Shale
Dark, organic-rich fine-grained sedimentary rock formed in oxygen-poor waters, often a source rock for oil and gas.
sedimentary
Rainbow Opal
Precious opal that displays a broad, vivid sweep of spectral colors, flashing the full rainbow as it is tilted in the light.
gemstone
Precious Opal
The classic gem opal that flashes shifting spectral colors, defined by the diffraction effect known as play-of-color.
gemstoneDragon Vein Agate
A treated chalcedony with a network of crackled veins, usually heated and dyed in vivid colors for affordable, eye-catching beads.
gemstoneWhiteschist
A rare high-pressure metamorphic schist defined by the diagnostic assemblage of talc plus kyanite, often pale and silvery.
metamorphic
Phosphorite
Phosphate-rich sedimentary rock, the world's main source of phosphorus for fertilizers, formed in nutrient-rich marine settings.
sedimentary
Turbidite
A graded sedimentary deposit laid down by underwater turbidity currents, recording avalanches of sediment cascading down submarine slopes.
sedimentaryDiatomite
A soft, lightweight, chalky sedimentary rock made of the silica shells of microscopic diatoms, prized for its absorbency and filtering ability.
sedimentaryAlabaster
A soft, fine-grained, translucent form of gypsum (or banded calcite) long prized as a carving and ornamental stone.
mineral
Anorthosite
An intrusive igneous rock made almost entirely of plagioclase feldspar, famous as the rock of the lunar highlands.
igneous
Andesine-Labradorite
An intermediate plagioclase feldspar spanning andesine and labradorite, marketed as a red-to-green gem, much of which is copper-diffusion treated.
gemstoneAutumn Jasper
A warm-toned jasper named for its autumn-leaf palette of browns, rust, gold, and cream, popular as soothing earth-tone beads.
mineralCat'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
Peridot
The gem-quality green variety of olivine, peridot is colored by iron and is one of the few gems found in only one color.
gemstone
Lavender Opal
A pastel purple variety of common opal, valued for its gentle lilac body color rather than any play-of-color.
gemstone
Honey Calcite
A warm golden-to-amber variety of calcite, a soft calcium carbonate mineral valued for its honeyed glow and easy carving.
mineral
Green Moonstone
A pale green variety of feldspar moonstone showing a soft white or bluish adularescent sheen over a greenish body.
gemstone
Red Opal
An opal with a deep red body color, often a variety of Mexican fire opal, prized for its warm, glowing intensity.
gemstone
Peach Tourmaline
A gentle peachy-pink tourmaline blending soft pink and orange tones, a delicate pastel variety of elbaite.
gemstone