General Information:
Chemical Formula:
NaZn(SO4)(OH)6Cl·6(H2O)
Composition:
(Molecular Weight = 626.20 gm)
Sodium 3.67 % Na
Zinc 41.77 % Zn
Hydrogen 2.90 % H
Sulfur 5.12 % S
Chlorine 5.66 % Cl
Oxygen 40.88 % O
Empirical Formula:
NaZn4(SO4)(OH)6Cl·6(H2O)
Environment:
In the oxidation zone of a hydrothermal vein deposit hosted by andesitic rocks.
IMA Status:
Approved IMA 1996 (Dana # Added)
Locality:
The San Francisco mine, 2 km northeast of the Sierra Groda Railway Station, in the Sierra Gorda, northeast of Antofagasta, 2nd region, northern Chile.
Name Origin:
Named after its locality.
Physical Properties:
Cleavage:
[001] Perfect
Color:
colorless or white.
Density:
2.627
Diaphaniety:
Transparent to translucent
Habits:
Platy - Sheet forms (e.g. micas)., Massive - Uniformly indistinguishable crystals forming large masses.,
Hardness:
2.5 - Finger Nail
Luminescence:
Non-fluorescent.
Luster:
Vitreous - Pearly
Streak:
white
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