General Information:
Chemical Formula:
(Mg,Fe++)2(Mg,Fe+++,Sn++++)O2(BO3)
Composition:
(Molecular Weight = 247.74 gm)
Magnesium 23.55 % Mg
Iron 11.27 % Fe
Tin 4.79 % Sn
Boron 8.73 % B
Oxygen 51.66 % O
Empirical Formula:
Mg2.4Fe2+0.25Fe3+0.25Sn0.1O2(BO3)
IMA Status:
Approved IMA
Name Origin:
Named for the composition and for Alfred Hulse Brooks (1871-1924), U. S. Geologist.
Physical Properties:
Cleavage:
None
Color:
black.
Density:
4.18
Diaphaniety:
Transparent to Translucent
Habits:
Aggregates - Made of numerous individual crystals or clusters., Microscopic Crystals - Crystals visible only with microscopes., Acicular - Occurs as needle-like crystals.
Hardness:
5.5-6.5
Luster:
Sub Metallic
Streak:
dark brown
More details...