List of rock types

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A list of all unique rock types recognized by petrologists. Names of non-rock types and archaic rock types are given as appendices.


A sample of andesite (dark groundmass) with amygdaloidal vesicules filled with zeolite. Diameter of view is 8 cm.
Andesite - an Intermediate volcanic rock
Alkali feldspar granite - a granitoid in which at least 90% of the total feldspar is in the form of alkali feldspar
Anorthosite - an intrusive igneous felsic rock composed predominantly of plagioclase
Aplite - a very fine grained intrusive igneous rock composed of quartz and feldspar
Basalt - a volcanic rock of mafic composition
Adakite - a class of basaltic rocks containing low amounts of yttrium and ytterbium
Hawaiite - a class of basalts formed from ocean island (hot spot) volcanism
Basanite - a volcanic rock of mafic composition; essentially a silica-undersaturated basalt
Boninite - a magnesium-rich basalt dominated by pyroxene
Carbonatite - a rare igneous rock composed of >50% carbonate minerals
Charnockite - a type of granite containing orthopyroxene
Enderbite - a variety of charnockite
Dacite - a felsic to intermediate volcanic rock containing hornblende and with plagioclase > orthoclase
Diabase or dolerite - an intrusive mafic rock forming dykes or sills
Diorite - a coarse-grained intermediate plutonic rock composed of plagioclase, pyroxene and/or amphibole
Dunite - a phaneritic ultramafic rock composed of more than 90% olivine, usually forsteritic
Essexite - a silica undersaturated mafic plutonic rock (essentially a foid-bearing gabbro)
Foidolite - a plutonic igneous rock composed of >90% feldspathoid minerals
Gabbro - a coarse grained plutonic rock composed of pyroxene and plagioclase basically equivalent to basalt
Granite - a coarse grained plutonic rock composed of orthoclase, plagioclase and quartz
Granodiorite - a granitic plutonic rock with plagioclase > orthoclase
Granophyre - a subvolcanic intrusive rock of granitic composition
Harzburgite - a variety of peridotite; an ultramafic cumulate rock
Hornblendite - a mafic or ultramafic cumulate rock dominated by >90% hornblende
Hyaloclastite - a volcanic rock composed primarily of glasses and glassy tuff
Icelandite - a volcanic rock
Ignimbrite - a fragmental volcanic rock
Ijolite - a very rare silica-undersaturated plutonic rock
Kimberlite - a rare ultramafic, ultrapotassic volcanic rock and a source of diamonds
Komatiite - an ancient ultramafic volcanic rock with very high MgO content
Lamproite - an ultrapotassic volcanic rock
Lamprophyre - an ultramafic, ultrapotassic intrusive rock dominated by mafic phenocrysts in a feldspar groundmass
Latite - a silica undersaturated form of andesite
Lherzolite - an ultramafic rock, essentially a peridotite
Monzogranite - a silica undersaturated granite with <5% normative quartz
Monzonite - a plutonic rock with <5% normative quartz
Nepheline syenite - a silica undersaturated plutonic rock with nepheline replacing orthoclase
Nephelinite - a silica undersaturated plutonic rock with >90% nepheline
Norite - a hypersthene bearing gabbro
Obsidian - a type of volcanic glass
Pegmatite - an igneous rock (or metamorphic rock) with giant sized crystals
Peridotite - a plutonic or cumulate ultramafic rock composed of olivine and pyroxene
Phonolite - a silica undersaturated volcanic rock; essentially similar to nepheline syenite
Picrite - an olivine-bearing basalt
Porphyry - a rock, usually granitic, with a porphyritic texture
Pumice - a fine grained, extremely vesicular volcanic rock
Pyroxenite - a coarse grained plutonic rock composed of >90% pyroxene
Quartz diorite - a diorite with >5% modal quartz
Quartz monzonite - an intermediate plutonic rock, essentially a monzonite with 5-10% modal quartz
Rhyodacite - a felsic volcanic rock which is intermediate between a rhyolite and a dacite
Rhyolite - a felsic volcanic rock
Comendite - a peralkaline rhyolite
Pantellerite - an alkaline rhyolite-rhyodacite with amphibole phenocrysts
Scoria - an extremely vesicular mafic volcanic rock
Sovite - a coarse grained carbonatite rock
Syenite - a plutonic rock dominated by orthoclase feldspar; a type of granitoid
Tachylyte - essentially a basaltic glass
Tephrite - a silica undersaturated volcanic rock
Tonalite - a plagioclase-dominant granitoid
Trachyandesite - an alkaline intermediate volcanic rock
Benmoreite - sodic trachyandesite
Basaltic trachyandesite
Mugearite - sodic basaltic trachyandesite
Shoshonite - potassic basaltic trachyandesite
Trachyte - a silica undersaturated volcanic rock; essentially a feldspathoid-bearing rhyolite
Troctolite - a plutonic ultramafic rock containing olivine, pyroxene and plagioclase
Trondhjemite - a form of tonalite where plagioclase-group feldspar is oligoclase
Tuff - a fine grained volcanic rock formed from volcanic ash
Websterite - a type of pyroxenite, composed of clinoproxene and orthopyroxene
Wehrlite - an ultramafic plutonic or cumulate rock, a type of peridotite, composed of olivine and clinopyroxene


File:Coalseam 8618.JPG
Bituminous coal seam in West Virginia
Dolomite crystals from Touissite, Morocco

File:Turbidite 2.JPG

Argillite - a sedimentary rock composed primarily of clay-sized particles
Arkose - a sedimentary rock similar to sandstone
Banded iron formation - a fine grained chemical sedimentary rock composed of iron oxide minerals
Breccia - a sedimentary or tectonic rock composed of fragments of other, broken rocks
Chalk - a sedimentary rock composed primarily of coccolith fossils
Chert - a fine grained chemical sedimentary rock composed of silica
Claystone - a sedimentary rock formed from clay
Coal - a sedimentary rock formed from organic matter
Conglomerate - a sedimentary rock composed of large rounded fragments of other rocks
Coquina - a sedimentary carbonate rock formed by accumulation of abundant shell fossils and fragments
Diamictite - a poorly sorted conglomerate
Diatomite - a sedimentary rock formed from diatom fossils
Dolomite or dolostone - a carbonate rock composed of the mineral dolomite +/- calcite
Evaporite - a chemical sedimentary rock formed by accumulation of minerals after evaporation; varieties include rock salt (halitite) and rock gypsum
Flint - a form of chert
Greywacke - an immature sandstone with quartz, feldspar and rock fragments within a clay matrix
Gritstone - essentially a coarse sandstone formed from small pebbles
Itacolumite - porous, yellow-orange sandstone which is flexible if cut into thin strips
Jaspillite - an iron-rich chemical sedimentary rock similar to chert or banded iron formation
Laterite - a residual sedimentary rock formed from a parent rock under tropical conditions
Lignite - a sedimentary rock composed of organic material; otherwise known as Brown Coal
Limestone - a sedimentary rock composed primarily of carbonate minerals
Marl - a limestone with a considerable proportion of silicate material
Mudstone - a sedimentary rock composed of clay and muds
Oil shale - a sedimentary rock composed dominantly of organic material
Oolite - a chemical sedimentary limestone
Sandstone - a clastic sedimentary rock defined by its grain size
Shale - a clastic sedimentary rock defined by its grain size
Siltstone - a clastic sedimentary rock defined by its grain size
Travertine - a sedimentary rock containing calcite and iron oxides
Turbidite - a particular sequence of sedimentary rocks which form within the deep ocean environment
Wackestone - a matrix-supported carbonate sedimentary rock.


Banded gneiss with a dike of granite orthogneiss


Anthracite - a type of coal
Amphibolite - a metamorphic rock composed primarily of amphibole
Blueschist - a metamorphic rock composed of sodic amphiboles with a distinct blue color
Cataclasite - a rock formed by faulting
Eclogite - an ultra-high grade metamorphosed basalt or gabbro; also a facies of metamorphic rocks
Gneiss - a coarse grained metamorphic rock
Gossan - the product of the weathering of a sulfide rock or ore body
Granulite - a high grade metamorphic rock formed from basalt; also a facies of metamorphic rocks
Greenschist - a mafic metamorphic rock dominated by green amphiboles
Hornfels - a metamorphic rock formed by heating by an igneous rock
Marble - a metamorphosed limestone
Migmatite - a high grade metamorphic rock verging upon melting into a magma
Mylonite - a metamorphic rock formed by shearing
Metapelite - a metamorphic rock with a protolith of clay-rich (siltstone) sedimentary rock
Phyllite - a low grade metamorphic rock composed mostly of micaceous minerals
Metapsammite - a metamorphic rock with a protolith of quartz-rich (sandstone) sedimentary rock
Pseudotachylite - a glass formed by melting within a fault via friction
Quartzite - a metamorphosed sandstone typically composed of >95% quartz
Schist - a low to medium grade metamorphic rock
Serpentinite - a metamorphosed ultramafic rock dominated by serpentine minerals
Skarn - a metasomatic rock
Slate - a low grade metamorphic rock formed from shale or silts
Suevite - a rock formed by partial melting during a meteorite impact
Talc carbonate - a metamorphosed ultramafic rock with talc as an essential constituent; similar to a serpentinite
Soapstone - essentially a talc schist
Whiteschist - a high pressure metamorphic rock containing talc and kyanite

Specific varieties of rocks

The following are terms for rocks that are not petrographically or genetically distinct but are defined according to various other criteria; most are specific classes of other rocks, or altered versions of existing rocks. Some archaic and vernacular terms for rocks are also included.

Adamellite - a variety of quartz monzonite
Appinite - a group of varieties of lamprophyre, mostly rich in hornblende
Aphanite - an aphanitic felsic volcanic rock which confounds identification via optical means
Borolanite - a variety of nepheline syenite from Loch Borralan, Scotland
Blue Granite - essentially larvikite, a monzonite
Epidosite - a type of metasomatite; essentially altered basalt
Felsite - an aphanitic felsic volcanic rock which confounds identification via optical means
Flint - typically a form of chert, jasper, or tuff
Ganister - a Cornish term for a palaeosol formed on sandstone
Ijolite - a silica-undersaturated plutonic rock associated with nepheline syenites
Jadeitite - a very rare rock formed by concentration of jadeite pyroxene; a form of serpentinite
Jasperoid - a hematite-silica metasomatite analogous to a skarn
Kenyte - a variety of phonolite, first found on Mount Kenya
Vogesite - a variety of lamprophyre
Larvikite - a variety of monzonite with microperthitic ternary feldspars from Larvik, Norway
Litchfieldite - a metamorphosed nepheline syenite occurrence near Litchfield, Maine
Luxullianite - a tourmaline-bearing granite with a peculiar texture, occurring at Luxulyan, Cornwall, England
Mangerite - a hypersthene-bearing monzonite
Minette - a variety of lamprophyre
Novaculite - a chert formation found in Oklahoma, Arkansas and Texas
Pyrolite - a chemical analogue considered to theoretically represent the earth's upper mantle
Rapakivi granite - a granite which exhibits the peculiar rapakivi texture
Rhomb porphyry - a type of latite with euhedral rhombic phenocrysts of feldspar
Shonkinite - melitilic and kalsititic rocks
Taconite - banded iron formation, primarily used in the United States of America
Teschenite - essentially a silica undersaturated, analcime bearing gabbro
Theralite - essentially a nepheline gabbro
Variolite - devitrified glass

See also

External links