Arseniosiderite - Encyclopedia
Class : Phosphates, arsenates, vanadates
Subclass : Hydrated Arsenates
Crystal System : Monoclinic
Chemistry : Ca2Fe3O2(AsO4)3 3H2O
Rarity : Uncommon
Arseniosiderite is a hydrated arsenate of iron and calcium. It is a secondary mineral which is formed by oxidation of arsenic minerals, mainly arsenopyrite and scorodite. It owes its name to its chemical composition arsenic plus siderite. Flattened, acicular crystals are rare and do not exceed 2 mm. Arseniosiderite forms much more readily fibroradiated aggregates or concretionary masses ranging in color from golden yellow to orange-brown and black-brown.
Main photo : Arseniosiderite from Romanèche, Saône-et-Loire, France © Rob Lavinsky
-macosiderite from Clara Mine, Germany © Franz Zöll
Arseniosiderite in the World
Photo : Arseniosiderite and bariopharmacosiderite from Clara Mine, Germany © Michael Förch
Twinning and special crystallizations
No known twin for this mineral species.
Fakes and treatments
No fake or treatments identified for this mineral species.
Hardness : 4.5
Density : 3.6
Fracture : Fibrous
Trace : Brown-yellow
TP : Opaque
RI : 1.792 to 1.898
Birefringence : 0.080
Optical character : Biaxial -
Pleochroism : Strong
Fluorescence : None
Solubility : Acids
Magnetism : None
Radioactivity : None