General Information:
Chemical Formula:(Mg,Fe++)2(Mg,Fe+++,Sn++++)O2(BO3)
Composition:(Molecular Weight = 247.74 gm)Magnesium 23.55 %
MgIron 11.27 %
FeTin 4.79 %
SnBoron 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
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