Esperanzaite

General Information:
 Chemical Formula:
NaCa2Al2(As+++++O4)2F4(OH)·2(H2O)
 Composition:
(Molecular Weight = 563.98 gm)
Sodium 4.08 % Na
Calcium 14.21 % Ca
Aluminum 9.57 % Al
Arsenic 26.57 % As
Hydrogen 0.89 % H 
Oxygen 31.21 % O 
Fluorine 13.47 % F 
 Empirical Formula:
NaCa2Al2(AsO4)2F4(OH)·2(H2O)
 Environment:
Found as a secondary phase on mineralized rhyolite.
 IMA Status:
IMA Approved (Dana # Added)
 Locality:
La Esperanza mine, Zaragosa mining district, near Madero, State of Durango, Mexico.
 Name Origin:
Named after the discovery locality.
Physical Properties:
 Cleavage:
[100] Perfect
 Color:
blue green.
 Density:
3.24
 Diaphaniety:
Transparent to Translucent
 Habits:
Botryoidal - "Grape-like" rounded forms (e.g.. malachite)., Spherical - Spherical, rounded aggregates.,
 Hardness:
4.5 - Between Fluorite and Apatite
 Luminescence:
Non-fluorescent.
 Luster:
Vitreous (Glassy)
 Streak:
white
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