Calcium Metatungstate, CaW₄O₁₃

Calcium Metatungstate, CaW₄O₁₃.10H₂O, is formed by the action of a hot solution of metatungstic acid on calcium carbonate. It crystallises with difficulty, yielding triclinic pinacoidal crystals,

a:b:c = 1.0070:1:1.3694; α = 91° 1'; β = 93° 0'; γ = 90° 16'.