General Information:
Chemical Formula:
(Fe++,Mg)2(Fe+++,Sn)O2(BO3)
Composition:
(Molecular Weight = 291.90 gm)
Magnesium 8.33 % Mg
Iron 36.35 % Fe
Tin 4.07 % Sn
Boron 7.41 % B
Oxygen 43.85 % O
Empirical Formula:
Fe2+MgFe3+0.9Sn0.1O2(BO3)
Environment:
Metamorphosed limestone at a granite contact.
Locality:
Brooks mountain, Seward peninsula, Alaska.
Name Origin:
Named for Alfred Hulse Brooks (1871-1924), U. S. Geologist.
Physical Properties:
Cleavage:
[110] Good
Color:
black.
Density:
4.3
Diaphaniety:
Opaque
Habits:
Crystalline - Fine - Occurs as well-formed fine sized crystals., Tabular - Form dimensions are thin in one direction.,
Hardness:
3 - Calcite
Luminescence:
Non-fluorescent.
Luster:
Sub Metallic
Streak:
black
More details...