Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Grandite Garnet
Grandite is an intermediate garnet between grossular and andradite, common in skarns and prized for vivid green to golden crystals.
mineral
Graphite Schist
A dark, foliated schist rich in graphite that leaves a grey-black mark and forms from metamorphosed carbon-rich sediments.
metamorphic
Dendritic Agate
A translucent chalcedony decorated with branching, fern-like manganese or iron oxide inclusions resembling tiny plants.
mineralPaintbrush Jasper
A scenic jasper whose flowing streaks of warm color resemble strokes left by a loaded paintbrush.
mineral
Amphibolite
A dark, dense metamorphic rock dominated by hornblende and plagioclase, formed by medium- to high-grade metamorphism of basalt.
metamorphic
Scenic Jasper
A patterned jasper whose bands and inclusions create miniature landscapes of deserts, mountains, and skies within the stone.
mineral
Gneiss
A high-grade metamorphic rock defined by alternating light and dark mineral bands, formed under intense heat and pressure.
metamorphic
Granodiorite
A common coarse-grained intrusive rock like granite but richer in plagioclase than potassium feldspar.
igneousMap Jasper
A patterned jasper whose outlined cells and contrasting borders resemble the boundaries and regions of a printed map.
mineral
Dendritic Opal
A common opal with branching, tree-like mineral inclusions that create natural fern, moss, or landscape patterns.
gemstone
Arkose
A coarse, feldspar-rich sandstone, often pink, that records rapid erosion of granitic source rock under arid conditions.
sedimentary
Garden Quartz
Clear quartz filled with mineral inclusions that look like underwater gardens, mossy landscapes, or floating scenery.
crystal
Picture Jasper
An opaque brown chalcedony whose iron-stained banding mimics deserts, dunes, and distant mountain skylines.
mineral
Gabbro
A coarse-grained, dark mafic intrusive rock that is the plutonic equivalent of basalt, rich in plagioclase and pyroxene.
igneousGrape Garnet
A trademarked deep purple-red rhodolite garnet from India, named for its rich grape-like color from the pyrope-almandine series.
gemstone
Grape Agate
Clusters of tiny botryoidal chalcedony spheres resembling bunches of grapes, famously purple, found in Indonesia.
mineral
Turbidite
A graded sedimentary deposit laid down by underwater turbidity currents, recording avalanches of sediment cascading down submarine slopes.
sedimentary
Tillite
A lithified glacial till, a poorly sorted rock of mixed boulders, pebbles and fine matrix that records ancient glaciations.
sedimentary
Calc-schist
A foliated metamorphic rock of calcite mixed with mica, quartz, and calc-silicate minerals, derived from marly sediments.
metamorphicMontana Garnet
Montana Garnet is red almandine recovered from Montana placer gravels, often alongside the state's famous sapphires.
gemstone
Ceylon Garnet
Ceylon Garnet is a historic trade name for fine red almandine (and hessonite) garnet from the gem gravels of Sri Lanka.
gemstoneColdwater Agate
A glacially transported agate found in Midwestern gravels, named for the Coldwater area, showing banded chalcedony patterns.
gemstone
Cherry Creek Jasper
A landscape-patterned Chinese jasper prized for warm cherry-red, cream, and green bands resembling painted scenery.
mineral
Moss Agate
A translucent chalcedony filled with green or brown dendritic mineral inclusions that resemble moss, foliage, or landscapes.
gemstone