Ferberite is a member that is rare of Wolframite mineral series that also includes Hübnerite. Hübnerite could be the manganese end that is rich while Ferberite is the Iron rich end member and Wolframite is the intermediate between your two. Ferberite is a small ore of Tungsten which is an important element that is industrial. Notable occurrences include Bolivia; Asia; England; Germany; Peru; Russia; South Korea; and Colorado, Idaho, New Mexico and South Dakota, USA. 

Category: Tungstate mineral
Formula: FeWO4
Iron(II) Wolframate
Crystallography: Monoclinic – Prismatic
Crystal Habit: Crystals are wedge-shaped, typically flattened and elongated, to 15 cm; faces striated; in groups of bladed crystals; massive
Twinning: Contact twins with composition plane; also interpenetrant or lamellar


Cleavage: [010] Perfect, [100] Parting, [102] Parting
Fracture: Uneven
Tenacity: Brittle
Hardness (Mohs): 4.0 – 4.5
Density: 7.50 – 7.60 (g/cm3)
Luminescence: None
Radioactivity: Not Radioactive
Other: Slightly Magnetic


Color: Black, Dark Brown on thin edges
Transparency: Nearly Opaque to Opaque; Transparent on thin edges
Luster: Adamantine, Metallic, Sub Metallic
Refractive Index: 2.255 – 2.414  Biaxial ( + )
Birefringence: 0.1590
Dispersion: Extreme; r > v
Pleochroism: n/a
Anisotropism: Distinct; bBireflectance: weak