Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Pelitic Schist
A schist derived from clay-rich sediments, rich in mica and often bearing index minerals like garnet, staurolite, or kyanite.
metamorphic
Turritella Agate
A brown fossiliferous chalcedony packed with spiral freshwater snail shells, technically agatized fossil rock from Wyoming.
sedimentaryWonderstone
A banded rhyolitic volcanic rock with swirling tan, red, and yellow iron-oxide layers prized as a decorative picture stone.
igneous
Dacite
A fine-grained volcanic rock intermediate between andesite and rhyolite, common at explosive stratovolcanoes.
igneous
Charnockite
A granite-like rock containing orthopyroxene, formed at high temperatures and pressures and often classed with the granulites.
igneousRainforest Jasper
An Australian green rhyolite with eye-like orbs and earthy patterns marketed as jasper, evoking dense rainforest foliage.
igneous
Alkali Feldspar
The feldspar solid-solution series between potassium feldspar and albite, a major rock-forming group spanning orthoclase, microcline, sanidine, and anorthoclase.
mineralSandstone
A clastic sedimentary rock made of cemented sand grains, often quartz, recording ancient beaches, deserts, and rivers.
sedimentary
Albite
The sodium end-member of the plagioclase feldspar series, a common white rock-forming mineral and parent of peristerite moonstone.
mineral
Norite
A coarse-grained mafic plutonic rock similar to gabbro but with orthopyroxene as the dominant pyroxene instead of clinopyroxene.
igneous
Anthracite
The highest-rank coal, a hard, lustrous black rock that burns cleanly with little smoke and high heat output.
metamorphic
Metaconglomerate
A conglomerate altered by heat and pressure, often with its rounded pebbles stretched and flattened into elongated lenses.
metamorphic
Seam Agate
Agate that forms in flat cracks or veins of host rock rather than rounded nodules, producing straight, parallel banding.
gemstone
Larvikite
A Norwegian intrusive rock whose feldspar crystals flash silvery-blue, widely used as blue pearl granite countertops.
igneousSlate
A fine-grained, low-grade metamorphic rock that splits into flat sheets along slaty cleavage, long used for roofing and flooring.
metamorphic
Bituminous Shale
A dark, organic-rich shale loaded with kerogen and bitumen that can yield oil and gas, often finely laminated and combustible.
sedimentary
Quartz-mica Schist
A foliated metamorphic rock of interlayered quartz and mica, producing a sparkling, easily split rock from metamorphosed sandy shales.
metamorphic
Biotite Schist
A foliated metamorphic rock dominated by glittering dark biotite mica, formed from mudstones under medium-grade regional metamorphism.
metamorphic
Anorthite
The calcium end-member of the plagioclase feldspar series, a high-temperature mineral common in mafic rocks, meteorites and lunar samples.
mineral
Greywacke
A hard, dark, poorly sorted sandstone with a muddy matrix, typically deposited by underwater turbidity currents.
sedimentary
Latite
The fine-grained volcanic equivalent of monzonite, an intermediate lava with nearly equal feldspars and little free quartz.
igneous
Tonalite
A quartz-rich plutonic rock dominated by plagioclase feldspar with little alkali feldspar, closely related to granodiorite and quartz diorite.
igneous
Feldspathic Sandstone
A feldspar-rich sandstone, often pink, that points to granitic source rocks eroded quickly in dry or cold climates.
sedimentary
Black Shale
Dark, organic-rich fine-grained sedimentary rock formed in oxygen-poor waters, often a source rock for oil and gas.
sedimentary