Ferberite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameFerberite
Chemical FormulaFeWO₄
Mohs Hardness4
Crystal Systemmonoclinic
Streak Colordark reddish brown to brownish black
Cleavageperfect on {010}
Fractureuneven to subconchoidal
Specific Gravity7.4
Colorsblack, brownish-black
Transparencyopaque
Type LocalityPanasqueira Mines, Panasqueira, Covilhã, Castelo Branco, Portugal
Mineral GroupTungstates
Usesore of tungsten, collector's specimens
Associated MineralsArsenopyrite, Siderite
Rarityuncommon
Description
A large, dark, metallic specimen displaying prominent bladed to columnar crystals of ferberite, with some duller, darker masses of associated minerals.
Geological Context
Ferberite typically forms in high-temperature hydrothermal veins, often associated with granitic intrusions, where it is a primary ore mineral for tungsten.
