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Table 2: The Organization of Sedimentary Rocks

 

Clastic (organized by grain

256+ mm: boulders

Conglomerate

size)

64-256 mm: cobbles

 

 

4-64 mm: pebbles

 

 

2-4 mm: granules

Sandstone

 

1-2 mm: course-grained sand

 

 

1 mm: medium-grained sand

 

 

1/16 mm: fine-grained sand

 

 

1/256 1/16 mm: silt

Siltstone

 

 

1/256 mm or smaller: mud, clay

Shale

Clastic (special circumstances)

Cemented fragments have sharp angles.

Breccia

 

Like sandstone, but has lots of feldspar.

Arkose

 

Like sandstone, but cement ads strong color.

Ferruginous sandstone

 

Like sandstone, but has lots of feldspar and some dark grains.

Graywacke

Chemical (organized by

NaCl

Rock Salt

chemical formula)

CaSO4 . 2H2O

Rock Gypsum

 

SiO2

Chert

 

CaMg(CO3)2

Dolomite

 

Various Other Minerals

Anhydrite, Hematite, Limonite, Goethite, some Borates, Nitrates, & Phosphates

 

CaCO3

Travertine,

Calcareous Tufa,

(Chemical) Limestone

Organic (organized by biological source)

Shells of ocean animals

(Shell) Limestone,

Coquina

 

Paleozoic trees & other plants

Lignite Coal,

Bituminous Coal

 

Mainly protozoa shells

Chalk

 

Mud, clay, plant & animal remains

Oil Shale

 

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