Ferrimolybdite - Encyclopedia
Class : Sulfates, chromates, molybdates
Subclass : Molybdates
Crystal system : Orthorhombic
Chemistry : Fe2(MoO4)3 8H2O
Rarity : Uncommon
Ferrimolybdite is the classic alteration mineral of molybdenum sulfides, it is found in the oxidation zone of hydrothermal molybdenum deposits. Its name is linked to its chemical composition (iron + molybdenum). Its usual appearance is that of a yellow to grayish-brown powder covering the molybdenite, but it can also appear in sheaves, in packets or in radiated aggregates of fine translucent canary yellow needles.
Main photo : Ferrimolybdite from Ochtiná, Slovakia © Martin Stevko
Ferrimolybdite in the World
Twinning
No twin known for this mineral species.
Fakes and treatments
No fakes recorded for this mineral species.
Hardness : 1 to 2
Density : 2.99
Fracture : Underterminated
Streak : Pale yellow
TP : Translucent to transparent
RI : 1.720 to 2.040
Birefringence : 0.130 to 0.230
Optical character : Biaxial +
Pleochroism : Visible
Fluorescence : None
Solubility : Hydrochloric acid
Magnetism : None
Radioactivity : None