Ogdensburgite

General Information:
 Chemical Formula:
Ca2(Zn,Mn)Fe+++4(AsO4)4(OH)6·6(H2O)
 Composition:
(Molecular Weight = 1,132.66 gm)
Calcium 7.08 % Ca
Manganese 0.97 % Mn
Zinc 4.62 % Zn
Iron 19.72 % Fe
Arsenic 26.46 % As
Hydrogen 1.60 % H 
Oxygen 39.55 % O 
 Empirical Formula:
Ca2Zn0.8Mn2+0.2Fe3+4(AsO4)4(OH)6·6(H2O)
 Environment:
Secondary Fe arsenate.
 IMA Status:
Approved IMA 1981
 Locality:
Sterling Hill mine, Ogdensburg, New Jersy, USA.
 Name Origin:
Named for the locality.
Physical Properties:
 Cleavage:
[001] Perfect, [010] Fair, [100] Poor
 Color:
brownish red, dark brown, or reddish orange.
 Density:
2.92 - 3.11, Average = 3.01
 Diaphaniety:
Translucent
 Habits:
Bladed - Aggregates of thin lath-like crystals (e.g. kyanite)., Encrustations - Forms crust-like aggregates on matrix., Micaceous - Platy texture with "flexible" plates.
 Hardness:
2 - Gypsum
 Luminescence:
Non-fluorescent.
 Luster:
Resinous
 Streak:
brown yellow
More details...