Ferberite

ferberite

scheelite

hubnerite

cassiterite

Images

Formula: Fe2+(WO4)
Anhydrous tungstate, a complete solid solution exists between ferberite and hübnerite.
Specific gravity: 7.51
Hardness: 4 to 4½
Streak: Black to brownish-black
Colour: Black
Solubility: Easily fusible. Slowly decomposed by hot concentrated sulphuric or hydrochloric acid. Decomposed by aqua regia with the separation of tungstic oxide.
Common impurities: Nb,Ta,Sc,Sn
Environments:

Pegmatites
Sedimentary environments
Metamorphic environments
Hydrothermal environments

Ferberite occurs in hydrothermal veins, medium temperature metamorphic rocks and granitic pegmatites immediately associated with granitic intrusive rocks; it also occurs in alluvial and residual deposits.
In high temperature (hypothermal) hydrothermal veins it is associated with cassiterite, arsenopyrite, apatite, tourmaline, topaz, fluorite, specular hematite, molybdenite and bismuth. In moderate temperature (mesothermal) veins it is associated with cassiterite and sulphides, scheelite, bismuthinite and siderite (Dana).

Localities

At Rumsby's mine, New South Wales, Australia, ferberite is the main ore mineral, associated with a granite intrusion, and it is commmonly intergrown with bismuth, arsenopyrite and fluorite. Some ferberite has altered to secondary scheelite. AJM 18.2.26

At Long Hill, Haddam, Middlesex county, Connecticut, USA, ferberite pseudomorphs after scheelite have been found (KL p215).

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