Powellite also is known to form as a primary mineral in quartz veins. Powellite forms an incomplete series with the mineral scheelite , CaWO 4 . Scheelite is a popular fluorescent mineral as it typically glows a bright bluish white. Powellite is less well known for its fluorescence, but some specimens can display a delightful golden yellow under ultraviolet light. Crystals of powellite resemble the much more common but heavier crystals of scheelite, fortunately the difference in fluorescence is a key to distinguishing them.
Color is yellow, brown, gray, blue, white or black.
Luster is adamantine to greasy. Crystals are translucent to transparent. Commonly as crusts or films around altered molybdenite and as pseudomorphs after molybdenite. Fracture is uneven. Hardness is 3.5 - 4.