General Information:
Chemical Formula:
BaMn+++2(Si2O7)(OH)2·(H2O)
Composition:
(Molecular Weight = 467.40 gm)
Barium 29.38 % Ba
Manganese 23.51 % Mn
Silicon 12.02 % Si
Hydrogen 0.86 % H
Oxygen 34.23 % O
Empirical Formula:
BaMn3+2(Si2O7)(OH)2·(H2O)
Environment:
As a replacement of NaMn amphibole nemansilite and serandite and as the main or sole constituent of tiny veinlets.
IMA Status:
Approved IMA 1996
Locality:
The Woods mine 30 km NNE of Tamworth, New South Wales, Australia.
Name Origin:
For William Noel Benson (1855-1957), of the University of Otago, in recognition of his pioneering research in the Great Serpentine Belt and New England Fold Belt of New South Wales, Australia.
Physical Properties:
Cleavage:
None
Color:
dark brown.
Density:
3.87
Diaphaniety:
Translucent to transparent
Habits:
Blocky - Crystal shape tends to be equant (e.g. feldspars)., Cryptocrystalline - Occurs as crystals too small to distinguish with the naked eye., Crystalline - Fine - Occurs as well-f ormed fine sized crystals.
Hardness:
4 - Fluorite
Luminescence:
Non-fluorescent.
Luster:
Vitreous - Greasy
Streak:
yellow brown
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