Chemical composition -- Lead molybdenate.
Color -- Various shades of orange, yellow, green, or brown.
Optics -- R.I 2.28-2.41.
Durability -- Hardness 2.5-3. Brittle.
Crystal structure -- Tetragonal.
Specific Gravity -- 6.5-7.0 (very dense).
Sources -- Many locations, including the U.S.A., Mexico, Austria, Morocco, Poland, Yugoslavia, New South Wales, etc.
Wulfenite is very fragile and difficult to cut and so is very rare in collections of finished stones. It is more often seen as magnificent crystal specimens.