WULFENITE, a mineral consisting of lead molybdate, PbMoO 4 , crystallizing in the hemimorphic-tetartohedral class of the tetragonal system. Crystals usually have the form of thin square plates bevelled at the edges by pyramidal planes. They have a brilliant resinous to adamantine lustre, and vary in colour from greyish to bright yellow or red: the hardness is 3, and the specific gravity 6-7. Small amounts of calcium are sometimes present isomorphously replacing lead. The mineral occurs in veins of lead ore, and was first found in the 18th century in the lead mines at Bleiberg in Carinthia. Bright yellow crystals are found in New Mexico and Utah, and brilliant red crystals in Arizona.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)