Metal is lustrous, silvery, and fairly soft when pure.
Usually obtained as gray powder. Used in alloys, electrodes, catalysts,
and as the sulfide, lubricants.
Diagnostic tests:
On charcoal molybdenum sulfide gives near the assay a copper-red stain in oxidizing
flame and white oxide further away.
On plaster, mixed with KI, gives a deep ultramarine blue color after
heating with the flame.
Bead tests using sodium phosphate (Na3PO4) gives a
yellowish green color (hot) and nearly colorless (cold), the reducing
flame color is a fine green.
Molybdates (MoO42-) are tested by adding powdered
sample to a dry test tube with a scrap of paper, adding a few drops of
water and an equal amount of concentrated H2SO4. The
mixture is carefully heated until the acid fumes. Cool or slowly add water
and the solution will assume a deep blue color.
If the molybdenum is in the form of the oxide or the sulfide then a yellowish green
flame test may be diagnostic.
References
Emsley, J., 1991; THE ELEMENTS : Sec. Ed.,
Clarendon Press, Oxford, 251 p.
(* - Mineral Name Is Not IMA Approved)
(! - New Dana classification added or changed from Danas New Mineralogy)
(? - IMA Discredited Mineral Species Name)
There are 45 minerals with Mo in the Mineralogy Database.