Salt
Salts can be found in all different colours: yellow (sodium chromate), orange (potassium dichromate), red (mercury sulphide), mauve (cobalt chloride hexahydrate), blue (copper sulfate pentahydrate, ferric hexacyanoferrate), green (nickel oxide), colorless (magnesium sulphate), white (titanium dioxide), and black (manganese dioxide). Most minerals and inorganic pigments, as well as many synthetic organic dyes, are salts.