In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula [SiO^(4-2x)_−4−x]_n, where 0 ≤ x < 2. The family includes orthosilicate SiO₄⁻⁴ (x = 0), metasilicate SiO₂⁻³ (x = 1), and pyrosilicate Si₂O₆−7 (x = 0.5, n = 2). The name is also used for any salt of such anions, such as sodium metasilicate; or any ester containing the corresponding chemical group, such as tetramethyl orthosilicate.[ The name "silicate" is sometimes extended to any anions containing silicon, even if they do not fit the general formula or contain other atoms besides oxygen; such as hexafluorosilicate [SiF6]²⁻.Most commonly, silicates are encountered as silicate minerals.