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Formula: FeMo2S4 (Fe2+Mo3+2S2-4)
Sulphide, molybdenum-bearing mineral
Crystal system: Monoclinic
Specific gravity: 5.445 calculated for the epirical formula
Hardness: 3
Streak: Dark grey
Colour: Grey
Magnetism: Slightly magnetic
Environments
Ferrodimolybdenite is a new mineral, approved in 2023 and to date (August 2025) reported only from the
type locality.
Localities
At the type locality, the Daba-Siwaqa complex, Transjordan Plateau, Amman Governorate, Jordan,
ferrodimolybdenite was discovered in a differentiated sulphide nodule composed of
troilite and pentlandite
parts. The nodule was detected in the central zone of a diopside –
anorthite – tridymite oval
paralava body, about 30 metres across, within the pyrometamorphic
complex. Ferrodimolybdenite is the first trivalent molybdenum
compound discovered in Nature, although a synthetic analogue is known. Ferrodimolybdenite was identified in
the troilite part of the nodule. The nodule contains inclusions of
tetrataenite,
nickelphosphide,
molybdenite, galena and
rudashevskyite. The ferrodimolybdenite forms platy crystals
with dimensions ranging from 3 × 100 μm to 20 × 40 μm.
The crystallisation of ferrodimolybdenite occurred in reduced conditions in monosulphide Fe(+Ni) melt at a
temperature of 1000 to 1100°C and at low pressure
(MM 89.2.242–249).
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