Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Chrome-Dravite
A chromium-dominant tourmaline related to dravite, producing intensely deep green to blackish-green crystals from chromium-rich metamorphic rocks.
mineral
Liddicoatite
A rare calcium-rich lithium tourmaline famous for the spectacular concentric color zoning seen in polished cross-section slices.
mineral
Garnet Schist
A shiny, foliated schist studded with red garnet crystals that grew during medium-grade regional metamorphism.
metamorphic
Calc-schist
A foliated metamorphic rock of calcite mixed with mica, quartz, and calc-silicate minerals, derived from marly sediments.
metamorphic
Red Jasper
An opaque, iron-rich variety of microcrystalline quartz known for its deep brick-red color and ancient history as a stone of strength and grounding.
gemstoneSard
A brownish-red to deep brown variety of chalcedony, closely related to carnelian but darker, colored by iron oxides.
mineralKiwi Jasper
A speckled green-and-black stone resembling kiwi fruit, technically a quartz-amazonite aggregate rather than true jasper.
mineralSmoky Obsidian
Translucent smoky-gray obsidian that transmits a hazy light, intermediate between clear and fully black volcanic glass.
igneousGondite
A metamorphic rock made chiefly of manganese-rich spessartine garnet and quartz, formed from ancient manganese-bearing sediments.
metamorphicLuxullianite
A distinctive tourmaline-rich granite from Cornwall, prized as an ornamental stone for its pink feldspar set with radiating black tourmaline.
igneous
Arkose
A coarse, feldspar-rich sandstone, often pink, that records rapid erosion of granitic source rock under arid conditions.
sedimentary
Syenite
A coarse-grained intrusive igneous rock dominated by alkali feldspar with little or no quartz.
igneous
Rubicline
An extremely rare rubidium-dominant alkali feldspar, the rubidium analogue of microcline, found in rare-element granitic pegmatites.
mineral
Tonalite
A quartz-rich plutonic rock dominated by plagioclase feldspar with little alkali feldspar, closely related to granodiorite and quartz diorite.
igneous
Dalmatian Jasper
A cream-colored spotted stone resembling a Dalmatian dog, made of feldspar and quartz dotted with dark mineral grains.
igneousSemiblack Opal
Opal with a dark grey body tone sitting between black and light opal, giving play-of-color rich contrast at an accessible price.
gemstone
Lamprophyre
A dark, mineral-rich dike rock with abundant mica or amphibole phenocrysts set in a fine groundmass, often associated with gold and diamonds.
igneous
Quartzite Sandstone
A tough, quartz-rich sandstone cemented by silica, transitional toward true quartzite but still sedimentary in origin.
sedimentary
Granite
A coarse-grained, speckled intrusive rock built from quartz, feldspar, and mica, forming the bedrock of the continents.
igneous
Dalmatian Stone
A cream-colored feldspar-and-quartz rock peppered with dark spots, named for its resemblance to a Dalmatian dog.
igneous
Wacke
A poorly sorted, muddy sandstone with abundant clay matrix between its grains, typically dark and deposited by turbidity currents.
sedimentary
Phyllite
A fine-grained foliated metamorphic rock between slate and schist, recognized by its silky silvery sheen and wavy, crinkled surfaces.
metamorphic
Dumortierite
A hard aluminum borosilicate famous for its rich denim-blue color, often forming dense fibrous masses or coloring quartz blue.
mineral
Verdite
A rich green, fuchsite-rich metamorphic rock from southern Africa, prized as a carving and ornamental stone.
metamorphic