COMMON ROCKS
(Igneous, Sedimentary, Metamorphic)
IGNEOUS
ROCKS
Igneous rocks form by the cooling &
crystallization of hot, molten rock (magma & lava). If this happens
at or near the land surface, or on the seafloor, they are extrusive igneous
rocks. If this happens deep underground, they are intrusive
igneous rocks.
Most igneous rocks have a crystalline texture, but
some are clastic, vesicular, frothy, or glassy.
GRANITE
BASALT
& OLIVINE BASALT ANDESITE
PORPHYRITIC
BASALT
VESICULAR
BASALT
VOLCANIC
BRECCIA VOLCANIC
TUFF
Classification
of igneous rocks (according to the British Geological Survey) (662 kb pdf)
SEDIMENTARY
ROCKS
Sedimentary rocks form by the solidification of loose
sediments. Loose sediments become hard rocks by the processes of
deposition, burial, compaction, dewatering, and cementation.
If the sediments are derived from weathering &
erosion of any previously existing rocks, you’ve got siliciclastic
sedimentary rocks.
If the sediments are derived from once-living
organisms (plants, animals, micro-organisms), you’ve got biogenic
sedimentary rocks.
If the sediments formed by inorganic chemical means,
you’ve got a chemical sedimentary rock.
Most sedimentary rocks have clastic textures, but some
are crystalline.
SANDSTONE
& GRAYWACKE SILTSTONE
SHALE
OOLITIC
LIMESTONE ONCOLITIC
LIMESTONE
CHERT
BANDED
IRON FORMATION PEAT
LIGNITE
COAL CANNEL
COAL BITUMINOUS
COAL
DOLOSTONE
ROCK
SALT ROCK
GYPSUM
DIATOMITE
OIL
SHALE TAR
SANDSTONE
Classification
of sedimentary rocks (according to the British Geological Survey) (459 kb
pdf)
METAMORPHIC
ROCKS
Metamorphic rocks result from intense alteration of
any previously existing rocks by heat and/or pressure and/or chemical
change. This can happen as a result of regional metamorphism
(large-scale tectonic events, such as continental collision or subduction), burial
metamorphism (super-deep burial), contact metamorphism (by the heat
& chemicals from nearby magma or lava), hydrothermal metamorphism
(by superheated groundwater), shear metamorphism (in or near a fault
zone), or shock metamorphism (by an impact event).
Many metamorphic rocks have a foliated texture, but
some are crystalline or glassy.
MARBLE
QUARTZITE
GREENSTONE
EPIDOTITE
DOLOMITIC
MARBLE SOAPSTONE
ECLOGITE
SLATE
PHYLLITE
SCHIST
GNEISS
MIGMATITE
GRANULITE
CHARNOCKITE
TECTONITE
SKARN
ANTHRACITE COAL
METACHERT
SERPENTINITE
METACONGLOMERATE
TECTONIC BRECCIA
Classification
of metamorphic rocks (according to the British Geological Survey) (260 kb
pdf)