Wulfenite, lead molybdate,
Formula PbMoO₄.

Crystal system: Monoclinic.
Hardness: 3
Density: 6.7 to 6.9 gms/cm³
Colour: Yellow or orange.
Streak: Yellowish white.

Wulfenite is a secondary mineral formed in the oxydation zones of lead and molybdenum ores. It is associated with galena, calcite, pyromorphite and vanadinite. Wulfenite is of only minor importance as a lead or molybdenum ore, being more valued as a mineral. Some of the finest crystalline specimens have come from the Red Cloud Mine in Arizona.

The specimen in the picture shows the smaller of two large, nicely-formed crystals of wulfenite on a bed of calcite. The specimen came from the Red Cloud Mine, La Paz County, Arizona, USA.