Cobalt Metatungstate, CoW₄O₁₃

Cobalt Metatungstate, CoW₄O₁₃.9H₂O, is obtained by double decomposition. According to Wyrouboff, the crystals contain 9.5H₂O and are rhombic bipyramids, with axial ratio,

a:b:c = 0.9878:1:1.3764.

Copper Metatungstate, CuW₄O₁₃.11H₂O, is obtained by Scheibler's method, and yields laminae and tables which probably belong to the monoclinic system. It forms a compound with ammonia.