A list of all unique rock types recognized by petrologists. Names of non-rock types and archaic rock types are given as appendices.
Igneous[]
tells you
A sample of andesite (dark groundmass) with amygdaloidal vesicules filled with zeolite. Diameter of view is 8 cm.
- Andesite - an Intermediate volcanic rock
- Anorthosite - an intrusive igneous felsic rock composed predominantly of plagioclase
- Aplite - a very fine grained intrusive igneous rock
- Basalt - a volcanic rock of mafic composition
- Adakite - a class of basaltic rocks containing low yttrium and ytterbium
- Hawaiite - a class of basalts formed from ocean island (hot spot) magmatism.
- Basanite - a volcanic rock of mafic composition; essentially a silica undersaturated basalt
- Boninite - a high-magnesian basalt dominated by pyroxene
- Carbonatite - a rare igneous rock composed of >50% carbonate minerals
- Charnockite - a type of granite containing pyroxene
- Enderbite - a variety of charnockite
- Dacite - a felsic to intermediate volcanic rock with high iron content
- 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
- 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
Sedimentary[]
tells you
Bituminous coal seam in West Virginia
Limey shale overlaid by limestone. Cumberland Plateau, Tennessee
Dolomite crystals from Touissite, Morocco
Turbidite (Gorgoglione Flysch), Miocene, South Italy
- 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
- Diamictite - a poorly sorted conglomerate
- Coquina - a sedimentary carbonate rock formed by accumulation of abundant shell fossils and fragments
- 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
- 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 sandstone
- 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
- Rock Gypsum-
- 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.
Metamorphic[]
tells you
Phyllite
Banded gneiss with a dike of granite orthogneiss
Marble
Quartzite
Manhattan Schist, from Southeastern New York
Slate
- 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
- Greenstone
- 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 + 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[]
- List of minerals
- List of rocks on Mars
- Rock cycle
- Rock formation: for a list of unusual or culturally significant rock outcrops.
External links[]
- British Geological Survey
- Igneous rock classification
- Classification of common rocks and soils
- Metamorphic Rock Classification
- Volcanic rocks
- Earth Science Education Unit virtual rock kit
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