Evaporites—formed by chemical precipitation from aqueous solution (ocean water)—
halite examples of an evaporate rock (mineral)
Form in inorganic chemical reaction, heat form sun causes water to evaporate form
seawater plus dissolved materials like chlorine, magnesium, sulfate, calcium, sodium,
carbonate, potassium, bicarbonate
As H20 is removed dissolved materials become more concentrated in seawater.
If enough water removed dissolved, materials become saturated in seawater, and if any
more H2) removed start to precipitate out of liquid.
For Ex: if 50% of water removed form seawater—calcite (CaCO3) precipitates out and
limestone is formed.
If 80% is removed, gypsum precipitates out.
90%--halite precipitates out
More water is removed—anhydrite
More water is removed—sylvite
Organic sedimentary rocks
Coal-sedimentary rock composed primarily of carbon. Various grades of coal identified
based upon how deep coal has been buried (thus exposed to higher temperatures and
Grades of coals are
Peat—Lowest Grade, Least C, Least Heat generation
Lignite—60-75% C, 17-34% O, 6.0% H, 0.5-3% S
Bituminous—75-91.5% C, 2.8%--10% O, 3.75-6% H, 1% S
Anthracite—Highest grade, Most C, Most Heat Generation >91.5%, <2.5% O, <3.75%