In chemistry, metatungstate refers to the anion with the formula [W<sub>12</sub>O<sub>40</sub>]<sup>8-</sup> and salts derived from this anion. The term also refers to protonated derivatives of this anion, including [H<sub>2</sub>W<sub>12</sub>O<sub>40</sub>]<sup>6-</sup>. The unprotonated anion [W<sub>12</sub>O<sub>40</sub>]<sup>8-</sup> has T<sub>d</sub> symmetry.