General Information:
Chemical Formula:
Ca2Fe+++Al2(SiO4)(Si2O7)(OH,O)2·(H2O)
Composition:
(Molecular Weight = 502.25 gm)
Calcium 15.96 % Ca
Aluminum 10.74 % Al
Iron 11.12 % Fe
Silicon 16.78 % Si
Hydrogen 0.80 % H
Oxygen 44.60 % O
Empirical Formula:
Ca2Fe3+Al2(SiO4)(Si2O7)(OH)2·(H2O)
Environment:
Metamorphic rocks.
Locality:
Langban, near Filipstad, Varmland, Sweden (actually the TL of julgoldite).
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
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...