Copper pyrites (copper), galena (lead), blende (zinc), cinnabar (mercury), &c. Of the sulphates we notice gypsum and anhydrite (calcium), barytes (barium) and kieserite (magnesium).
Thus the sulphate constitutes the minerals anhydrite, alabaster, gypsum, and selenite; the carbonate occurs dissolved in most natural waters and as the minerals chalk, marble, calcite, aragonite; also in the double carbonates such as dolomite, bromlite, barytocalcite; the fluoride as fluorspar; the fluophosphate constitutes the mineral apatite; while all the more important mineral silicates contain a proportion of this element.
The salt is commonly associated with gypsum, often also with anhydrite, and occasionally with sylvite, carnallite and other minerals containing potassium and magnesium.
Deeper down there are successively strata of polyhalite, MgS04 K2S04.2CaS04.2H20, and anhydrite, CaSO 4, interspersed with regular layers of rock-salt; whilst below the anhydrite we have the main rock-salt deposits.
The normal sulphates are the more important, and occur widely and abundantly distributed in the mineral kingdom; anhydrite, gypsum, anglesite, barytes, celestite and kieserite are among the commonest species.