ROCK NAME

How Recognized

From What Sediments

Origin Identification

Coal Bituminous

Black to brown color; soft; will burn

Plant remains

Organic

Chalk/Limestone

Soft, crumbly; may contain fossil shell

Shells, shell fragments, coral fragments

Organic

Coquina

Porous, all-shell rock

Shells, shell fragments, coral fragments

Organic

Conglomerate

Round pebbles or angular fragments

Gravel

Clastic

Breccia

Round pebbles or angular fragments

Gravel

Clastic

Sandstone

Cemented sand grains, gritty, any color

Sand

Clastic

Shale

Clay/mud with flat fracture, earthy odor

Clay or mud

Clastic

Dolomite/Limestone

May be fossiliferous, effervescent in weak acid

Limy mud

Chemical

Chert

Scratches glass, called flint when dark

Silica

Chemical

Gypsum

Easily scratched, variety of colors, clear

Calcium sulfate plus water

Chemical