General Information:
Chemical Formula:
Ca2(Mn++,Mg)(Al,Mn+++,Fe)2(SiO4)(Si2O7(OH)2·(H2O)
Composition:
(Molecular Weight = 504.86 gm)
Calcium 15.88 % Ca
Magnesium 1.20 % Mg
Manganese 16.32 % Mn
Aluminum 5.34 % Al
Iron 2.77 % Fe
Silicon 16.69 % Si
Hydrogen 0.60 % H
Oxygen 41.20 % O
Empirical Formula:
Ca2Mn2+0.75Mg0.25AlMn3+0.75Fe3+0.25(SiO4)(Si2O7)(OH)·(H2O)
Environment:
Metamorphosed Mn-oxides in pelitic and dolomitic rocks.
IMA Status:
Approved IMA 1980
Locality:
Ochiai mine, Barazawa, Kohsai-cho, Yamanashi Prefecture, Japan.
Name Origin:
Named after the American geologist, R. Pumpelly (1837-1923).
Physical Properties:
Cleavage:
[001] Good, [100] Good
Color:
blue green, olive green, or brown.
Density:
3.2
Diaphaniety:
Transparent to Translucent
Habits:
Spherical - Spherical, rounded aggregates., Fibrous - Crystals made up of fibers., Massive - Lamellar - Distinctly foliated fine-grained forms.
Hardness:
5.5 - Knife Blade
Luster:
Vitreous (Glassy)
Streak:
white
More details...