Magnesium Metatungstate, MgW4O13.8H2O, is obtained by double decomposition. It yields lustrous monoclinic prisms with
a:b:c = 0.6763:1:0.7792; β = 106° 43'.
Manganous Metatungstate, MnW4O13.10H2O, is also obtained by double decomposition. It forms beautiful light yellow quadratic octahedra, a:c = 1:0.9919, permanent in the air. On heating at 100° C. to 110° C. it loses 7H2O, the remaining 3H2O only being expelled at a much higher temperature. |