EARTH SCIENCE LAB
Sedimentary Sample #7:
Identify the Texture, Grain Size, Composition and Rock Type
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Sedimentary Rock Identification Chart
TEXTURE
GRAIN SIZE
COMPOSITION
ROCK NAME
Clastic
>2 mm
rounded quartz, feldspar and rock fragments
Conglomerate
>2 mm
angular quartz, feldspar and rock fragments
Breccia
1/16 - 2 mm
quartz, feldspar
Sandstone
>1/16 mm
feldspar, quartz
Arkose
<1/16 mm
quartz, clay minerals
Siltstone
(Mudstone, Shale)
<1/256 mm
quartz, clay minerals
Claystone
Chemical
no grain size
silica (quartz)
Chert
dolomite
Dolostone
calcite
Limestone
halite
Rock Salt
gypsum
Rock Gypsum
Biologic
no grain size
silica (quartz)
Chert
loosely compacted organic material
and plant fragments
Peat
densely compacted organic material
and plant fragments
Bituminous Coal
calcite
Limestone
calcite, micro-skeletal fragments
Chalk
calcite, almost entirely shell
and skeletal fragments
Coquina
calcite with some shell
and skeletal fragments
Fossiliferous Limestone
dolomite with some shell
and skeletal fragments
Fossiliferous Dolostone
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