Lead Molybdates

The normal salt, PbMoO₄, occurs in nature as wulfenite. It may be obtained in the crystalline form by fusing together lead chloride and sodium molybdate. The light yellow transparent crystals belong to the tetragonal system, with axial ratio a:c = l:1.5771, and have density 6.811, hardness 2.75 to 3.0, and melting-point 1065° C. Lead molybdate is also obtained in the amorphous form by addition of lead nitrate solution to a solution of an alkali molybdate or paramolybdate, when it separates quantitatively as a white precipitate. A basic molybdate, 2PbO.MoO₃, and an acid molybdate, 2PbO.5MoO₃, have been described.