Arseniosiderite – Occurrence, Properties, and Distribution

Topics Covered

Introduction to Arseniosiderite
Properties of Arseniosiderite
How to Identify Arseniosiderite
Global Distribution
Occurrence of Arseniosiderite and Useful Mineral Association
References

Introduction to Arseniosiderite

Chemical Formula – Ca2Fe3+3 O2(AsO4)3 •3H2O

Arseniosiderite was named by Pierre Armand Petit Dufrenoy in 1842, after the mineral's key elements - arsenic and iron ("sideros" in Greek). It belongs to the mitridatite group.

Properties of Arseniosiderite

The following are the key properties of arseniosiderite:

  • Cell Data
    • Space group: [A2/a]
    • a = 17.76(4)
    • b = 19.53(1)
    • c = 11.30(1)
    • β = 96.0°
    • Z = 12

 

  • Crystal Data
    • Monoclinic, pseudotetragonal
    • Point group: 2/m
    • Euhedral crystals very rare, to 2mm
    • As flattened fibers, in radial aggregates, and felted to granular masses
    • X-ray powder pattern: 8.84 (10), 2.772 (8), 5.62 (5), 2.945 (5), 3.28 (4), 3.22 (4), 2.213 (4)

 

  • Chemical Composition
    Elements Content 1 Content 2
    As2O5 42.67 45.94
    Fe2O3 32.71 31.92
    CaO 14.44 14.94
    H2O 9.34 7.20
    MgO 0.61 -
    insol. 0.40 -
    PbO 0.28 -
    FeO 0.12 -
    Total 100.57 100.00

 

  • Optical Properties
    • Optical class: Biaxial (-)
    • Pseudouniaxial (-)
    • Pleochroism: Strong; X = nearly colorless to pale brownish or brownish-red; Y = Z = brownish-red to dark reddish-brown
    • Absorption: Y = Z » X
    • α = 1.792–1.815; β = 1.870–1.898; γ = 1.870–1.898
    • 2V(meas.) = Small

 

  • Estimated Properties
    Electron density Bulk density (electron density) = 3.75 g/cm3
    note: Specific gravity of arseniosiderite = 3.92 g/cm3
    Photoelectric PEArseniosiderite = 27.84 barns/electron
    U=PEArseniosiderite x ρ electron density = 104.49 barns/cm3
    Fermion index Fermion index = 0.004956593
    Boson index = 0.995043407
    Radioactivity
    Arseniosiderite is not radioactive

How to Identify Arseniosiderite

Arseniosiderite can be identified in the field by its color variations, such as bronze-brown, yellow, yellow-brown, dark brown, and black. Its translucent to opaque form has {100} good cleavage. This mineral has a sub-metallic luster, with ochraceous streak.

The density of arseniosiderite is 3.5 to 3.9 g/cm3 with a hardness of 1.5 - between talc and gypsum. It is non-fluorescent.

Global Distribution

Arseniosiderite is distributed in the following places:

  • France - From Romaneche, Saone-et-Loire
  • Germany - At Schneeberg, Saxony, and at Wittichen and Neubulach, Black Forest
  • England – At Carrock and Caldbeck Fells, Cumbria; from the Penberthy Croft mine, St. Hilary, Cornwall; in the Huckworthy Bridge mine, Sampford Spiney, Devon
  • Austria - At Huttenberg, Carinthia
  • Namibia - At Tsumeb
  • Australia - Found at the Dome Rock copper mine, about 40km northwest of Mingary, South Australia
  • Greece - From the Kamariza mine, Laurium
  • Bolivia - In the Negra mine, near Cosca, north of Ollague
  • USA - From Sterling Hill, Ogdensburg, Sussex Co. New Jersey; at the Mohawk mine, San Bernardino Co. and in the Kalkar quarry, Santa Cruz, Santa Cruz Co. California; from the Gold Hill mine, Tooele Co. and the Mammoth and other mines, Tintic district, Juab Co. Utah
  • Mexico - From the Jesus Maria mine, Mazapil district, Zacatecas; in the Ojuela mine, Mapimi, Durango; and at the Las Animas mine, La Mur, Sonora

Occurrence of Arseniosiderite and Useful Mineral Association

Arseniosiderite occurs as a rare secondary mineral, formed by the oxidation of earlier arsenic-bearing minerals such as scorodite or arsenopyrite.

It is often associated with minerals such as beudantite, arsenopyrite, scorodite, dussertite, carminite, pharmacolite, adamite, erythrite, lollingite, and pitticite.

References

 

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