D. CHEMICAL SEDIMENTARY ROCKS

1. Limestone - composed mostly of the mineral calcite. CaCO3 120, 121, 122

a. precipitated in shallow seas by organisms

b. accumulations of shells - most limestone is made of broken fragment of coral, shells, and algae (these would be clastic sedimentary rocks).

2. Dolostone - composed of the mineral dolomite (Ca, Mg)CO3

3. Chert - fine-grained quartz - hard and compact; two varieties are flint and agate. 122

a. precipitated from ocean water

b. accumulations of plant/animal parts - diatoms > diatomaceous earth

4. Evaporites - sedimentary rocks formed of material precipitated from solution by evaporation of water when a restricted basin dries up. Examples include halite, gypsum, and borates 125

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