Ferberite ( Fe++WO4)
FeWO4

Color

Black

Cleavage

{010} Perfect, {100} Parting, {102} Parting

Density

7.5 - 7.4, Average = 7.45

Diaphaneity

Nearly opaque

Hardness

4.5 - Between Fluorite and Apatite

Gladstone-Dale

Cl meas = -0.016 (Superior) - where the Cl = (1-KPDmeas/KC)
Cl calc  =  0.002 (Superior) - where the Cl = (1-KPDcalc/KC)
KPDcalc = 0.1748, KPDmeas = 0.1778, KC = 0.175
Ncalc = 2.3 - 2.33

Optical Data

Biaxial (+) 
a = 2.255, b = 2.305. g = 2.414
bire = 0.1590, 2V(Calc) = 72, 2V(Meas) = 68

RL Bireflectance

Weak

Refectivity

400nm

16.50

19.50

420nm

16.40

19.20

440nm

16.30

18.90

460nm

16.20

18.70

480nm

15.90

18.50

500nm

16.00

18.70

520nm

16.00

18.70

540nm

16.00

18.70

560nm

16.00

18.70

580nm

15.80

18.60

600nm

15.80

18.60

620nm

15.70

18.60

640nm

15.60

18.50

660nm

15.50

18.30

680nm

15.40

18.10

700nm

15.50

18.00

Composition

Molecular Weight = 303.69 gm

Axial Ratios

a:b:c = 0.838:1:0.8661

Cell Dimensions

a = 4.76
b = 5.68
c = 4.92
Z = 2
beta = 90.016° 
V = 133.02 Den(Cal) = 7.58

Crystal System

Monoclinic - Prismatic 
H-M Symbol (2/m) Space Group: P 2/c

Orientations

[110]  [110] [100] [011] [001]

Electron Density

Bulk Density (Electron Density) = 6.59 gm/cc
Specific Gravity of Ferberite = 7.58 gm/cc

Fermion Index

Fermion Index = 0.09
Boson Index = 0.91

Photoelectric

PEFerberite = 757.55 barns/electron
U = PEFerberite x rElectron Density = 4,991.71 barns/cc