Sedimentary Rock Classification

SEDIMENTARY ROCK CLASSIFICATION TEXTURE(Clastic) COMPOSITION/CHARACTERISTICS ROCK NAME Gravel Size (over Rounded fragments of any rock type Conglomerate 2mm) mixed sizes of rock fragments, general forms in fast moving water such as in a river. Sand Size Quartz with minor amounts of other Sandstone minerals. Sand may be any color. Feels like a nail file. Generally forms in shallow moving water along a river bank or beach. Silt Size Quartz and mud minerals. Layered. Siltstone Commonly has leaf or plant fossils. Forms in calm deep water such as in a lake or off-shore in the ocean. Clay Size Quartz and clay minerals. Very fine Red Shale mud. Often layered. Frequently black in color, but may be red or Oil Shale green. Forms only in very quiet, deep water. ORGANIC ROCKS CHARACTERISTICS COMPOSITION/FORMATIO ROCK NAME N Loosely cemented Calcium Carbonate Shells, Coquina shells, resembles forms near coral reef in oatmeal shallow warm ocean water. Grey colored, Calcite, forms near reef Limestone commonly with fossils, environments in shallow oceans. reacts to dilute acid Similar to limestone Calcite with fossils visible, Fossil Limestone but often pink or light forms in reef environment in brown in color. shallow ocean. Brown to black, Carbon, forms in places that Coal layered, may contain were once swamps or heavily plant remains vegetated. CHEMICAL ROCKS

Variety of colors, Silica, forms in deep water Chert sharp edges, made of where silica is abundant. quartz Crystalline, layered, Gypsum, forms in desert Gypsum soft, usually light environments where water in colored shallow lakes or ponds evaporates. Clear, breaks into Forms from evaporation from Rock Salt/Halite squares lakes or ocean