Sediments and chemical sedimentary rocks are classified according to chemical composition and can be:
Carbonatics: formed by the accumulation of carbonate minerals (limestone and dolomites) - the most common on Earth. Can be generated by reefs, inorganic reactions or even of mixed origin.
Evaporites: formed by the precipitation of salts in the evaporation of seawater and lakes in closed arid regions. The Marine evaporites are common in regions where the freshwater supply is small, the sea is closed and the climate is arid.
There are also silica rocks (chert / precipitated silica - flint), phosphorites and ferruginous rocks. As well as oil basins, coal and natural gas, formed by the action of high temperatures and pressures on organic waste.
