List of rock types

List
Sorted by name; initial letter means Igneous, Sedimentary or Metamorphic rocks.
A
I Andesite - an intermediate volcanic rock
M Anthracite - a form of hard coal
B
S Banded iron formation - a fine grained chemical sedimentary rock composed of iron oxide minerals
S Bauxite - the main ore of aluminium. It is mostly aluminium oxide.
I Basalt - grey/black fine-grained rock from lava which cooled on the surface of the Earth.
S Blue Lias - a formation of rocks, part of the Jurassic Coast World Heritage Site.
S Breccia - a sedimentary or tectonic rock composed of fragments of other, broken rocks
C
S Chalk - a fine grained carbonate rock composed mainly of coccoliths
S Chert - a fine grained chemical sedimentary rock composed of silica
S Clastic rock - composed of fragments, or clasts, of pre-existing rock.
S Claystone - a sedimentary rock formed from clay
S Coal - a sedimentary rock formed from peat
S Concretion - a concretion is a rock in which a mineral cement fills the spaces between the sediment grains.
S Conglomerate - a sedimentary rock composed of large rounded fragments of other rocks
S Coquina - a sedimentary carbonate rock formed by accumulation of abundant shell fossils and fragments
D
I Dacite - a felsic to intermediate volcanic rock with high iron content
S Diatomite - a sedimentary rock fromed from diatom fossils
I Diorite - a coarse grained intermediate plutonic rock
S Dolomite - a carbonate rock composed of calcium magnesium carbonate: CaMg(CO3)2
I Dunite - a rock made mostly of olivine
E
Evaporite - a chemical sedimentary rock formed by accumulation of minerals after evaporation
F
S Flint - a form of chert
I Foidolite - a plutonic igneous rock composed of >90% feldspathoid minerals
G
I Gabbro - a coarse grained plutonic rock chemically equivalent to basalt. Plutonic = magma cooled below surface of the Earth.
M
I Granite - a coarse grained plutonic rock composed of orthoclase, plagioclase and quartz
M Granulite - a high grade metamorphic rock formed from basalt; also a facies of metamorphic rocks
M Greenschist - a generic term for a mafic metamorphic rock dominated by green amphiboles
S Greenstone - greenish sandstone; and a geologic formation in Great Britain
S Greywacke - an immature sandstone with quartz, feldspar and rock fragments within a clay matrix
S Gritstone - a coarse sandstone formed from small pebbles
H
I Horneblendite - a mafic or ultramafic cumulate rock dominated by >90% hornblende
M Hornfels - a metamorphic rock formed by heating by an igneous rock
I
I Ignimbrite - a fragmental volcanic rock
K
I Kimberlite - a rare ultramafic, ultrapotassic volcanic rock and a source of diamonds
L
S Lignite - brown coal
S Limestone - a sedimentary rock composed primarily of carbonate minerals
M
M Marble - a metamorphosed limestone
S Marl (geology) - a limestone with a considerable proportion of silicate material
M Migmatite - a high grade metamorphic rock verging upon melting into a magma
S Mudrock - a sedimentary rock composed of clay and muds
S Mudstone - a type of mudrock
N
I Nephelinite - a silica undersaturated plutonic rock with >90% nepheline
O
I Obsidian - volcanic glass
S Woolite - a chemical sedimentary limestone (formed by precipitation)
P
I Pegmatite - an igneous rock (or metamorphic rock) with giant sized crystals
I Peridotite - a plutonic or cumulate ultramafic rock composed of >90% olivine
M Phyllite - a low grade metamorphic rock composed mostly of micaceous minerals
I Plutonic rocks - intrusive rocks that crystallized from magma slowly cooling below the surface of the Earth.
I Pumice - a fine grained volcanic rock with gas bubbles inside
I Pyroclastic rocks - rocks of volcanic origin
Q
M Quartzite - a metamorphosed sandstone typically composed of >95% quartz
R
I Rhyolite - a felsic volcanic
S
S Sandstone - a clastic sedimentary rock defined by its grain size
M Schist - a low to medium grade metamorphic rock
M Serpentinite - a metamorphosed ultramafic rock dominated by serpentine minerals
S Shale - a clastic sedimentary rock defined by its grain size
S Siltstone - a clastic sedimentary rock defined by its grain size
M Skarn - calcium-bearing silicate rocks of any age: a metasomatic rock
M Slate - a low grade metamorphic rock formed from shale or silts
M Steatite - Steatite or soapstone is a metamorphic rock. It has a large amount of the mineral talc.
I Syenite - a plutonic rock dominated by orthoclase feldspar; a type of granitoivolcanic rock; can be a generic term
T
I Tonalite - a plagioclase-dominant granitoid
S Travertine - a carbonate precipitate from hot-springs.