Gypsum $ \text{(CaS}{{\text{O}}_{4}}\text{.2}{{\text{H}}_{2}}\text{O)} $ is an ore of calcium. Dolomite $ \text{(CaS}{{\text{O}}_{3}}\text{.MgC}{{\text{O}}_{3}}\text{),} $ magnesite $ (MgC{{O}_{3}}) $ and camallite $ (KCl.MgC{{l}_{2}}.6{{H}_{2}}O) $ are the ores of magnesium.