List of rock types

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

Igneous

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) magmatism.

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 pyroxene

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

Sedimentary

Main article: Sedimentary rock

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

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.

Metamorphic

Main article: Metamorphic rock

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
• Rock Types Article by Encyclopaedia Britannica
• Classification of common rocks and soils
• Metamorphic Rock Classification
• Volcanic rocks
• Earth Science Education Unit virtual rock kit