Fluoride , is an inorganic anion of fluorine with the chemical formula . It contributes no color to fluoride salts. Fluorite is roughly 49% fluoride by mass, making fluoride the main component of fluorite apart from calcium ions. Fluoride contributes a distinctive bitter taste, but no odor to fluoride salts. Its salts are mainly mined as a precursor to hydrogen fluoride. Although it is classified as a weak base, concentrated fluoride solutions are corrosive and can attack the skin. Fluoride is the simplest unary fluorine anion, the other being the tentatively investigated difluoridofluorate(1-) anion. Its salts are important chemical reagents and industrial chemicals, mainly used in the production of hydrogen fluoride for fluorocarbons. Structurally, and to some extent chemically, the fluoride ion resembles the hydroxide ion. Fluoride ions occur on earth in several minerals, particularly fluorite, but are only present in trace quantities in water.