Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Mookaite
A vivid Australian jasper-like silica stone in earthy reds, yellows, and purples, formed from silicified radiolarian sediment.
mineral
Woodbine 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
Bekily Garnet
A rare color-change garnet from Bekily, Madagascar, shifting from bluish-green in daylight to purplish-red under warm light, including the famed blue garnets.
gemstone
Pele's Hair
Fine, golden, hair-like strands of basaltic volcanic glass spun from fluid lava droplets during eruptions, named for the Hawaiian volcano goddess.
igneous
Pele's Tears
Small, smooth, teardrop-shaped beads of basaltic volcanic glass formed from airborne lava droplets, often paired with Pele's hair.
igneous
Pearl
An organic gem formed inside mollusks from layered nacre, prized for its iridescent luster and classic elegance.
gemstone
Chalcocite
A dark gray copper sulfide that is one of the richest copper ores, prized by collectors when found as rare sharp crystals.
mineral
Sherry Tourmaline
A warm sherry-brown to orange-brown tourmaline, usually magnesium-rich dravite, named for its rich fortified-wine color.
gemstone
Reedmergnerite
A rare boron-bearing feldspar, the boron analogue of albite, first found in oil-shale nodules of the Green River Formation.
mineral
Mylonite
A fine-grained, strongly foliated rock formed deep in fault zones where rocks flowed and ground down rather than fracturing.
metamorphic
Copper
A soft, reddish native metal with excellent conductivity, mined for wiring, plumbing, and alloys like bronze and brass.
mineral
Spessartite Garnet
A manganese aluminum garnet glowing in vivid orange to reddish-orange tones, with the finest called mandarin garnet.
gemstone
Rutilated Quartz
Clear or smoky quartz threaded with golden to reddish needles of rutile, also poetically called Venus hair stone.
crystal
Purple Tourmaline
An uncommon purple to violet tourmaline colored by manganese, the deeper reddish-purple stones sometimes called siberite.
gemstone
Monazite
A reddish-brown rare-earth phosphate that is a primary ore of cerium, thorium and other rare-earth elements, often found in placer sands.
mineral
Cognac Tourmaline
A warm cognac-brown to reddish-brown tourmaline, typically magnesium-rich dravite, prized for its rich whisky-like color.
gemstone
Color Change Garnet
A rare garnet that dramatically shifts color from greenish in daylight to reddish under lamplight, rivaling alexandrite.
gemstone
Andalusite
A pleochroic aluminum silicate that flashes green and reddish-brown from different angles, with a cross-marked variety called chiastolite.
mineral
Brecciated Agate
Agate that was shattered and naturally re-cemented by silica, creating a mosaic of angular fragments in a quartz matrix.
gemstone
Ruin Agate
A fractured and re-cemented agate whose angular broken bands resemble crumbling walls and ruined cityscapes when polished.
gemstone
Faden Quartz
Tabular quartz crossed by a milky white thread-like line marking where the crystal repeatedly cracked and re-healed.
crystal