Geology Wiki

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


tells you

File:Amygdaloidal andesite.jpg

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


tells you

File:Coalseam 8618.JPG

Bituminous coal seam in West Virginia


Limey shale overlaid by limestone. Cumberland Plateau, Tennessee

File:Dolomite Morocco.jpg

Dolomite crystals from Touissite, Morocco

File:Turbidite 2.JPG

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.


tells you




Banded gneiss with a dike of granite orthogneiss



File:Quartzite 2 jpg.jpg



Manhattan Schist, from Southeastern New York



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 + 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[]

Template:Link GA