Abswurmbachite – Occurrence, Properties, and Distribution

Abswurmbachite was discovered in 1990 and named after a German mineralogist, Dr. Irmgard Abs-Wurmbach.

Properties of Abswurmbachite

The following are the key properties of Abswurmbachite:

  • Cell Data
    • Space group: [I41/acd.]
    • a = 9.406(1)
    • c = 18.546(3)
    • Z = [8]

  • Crystal Data
    • Tetragonal (by analogy to braunite)
    • Point group: [4/m 2/m 2/m]
    • Anhedral grains, to 50µm
    • X-ray powder pattern: Synthetic (Cu 0:98 Mn2+0:02) Σ=1:00Mn 3+6 SiO12
    • 2.702 (100), 1.6507 (30), 2.350 (15), 2.133 (15), 1.459 (14), 1.4016 (11), 1.6627 (10)

  • Chemical Composition
    Elements Content
    Mn2O3 72.1
    CuO 11.6
    SiO2 10.1
    Fe2O3 4.7
    TiO2 0.23
    Al2O3 0.58
    CaO 0.16
    MgO < 0.04
    Total 99.47

  • Optical Properties

    Although black in color to the naked eye, Abswurmbachite is gray in reflected light, with a brownish-black streak. Its anisotropism is weak.

  • Estimated Properties
    Electron density Bulk density (electron density) = 4.70 gm/cm3
    note: Specific gravity of Abswurmbachite = 4.98 gm/cm3
    Photoelectric PEAbswurmbachite = 18.79 barns/electron
    U = PEAbswurmbachite x ρElectron density = 88.29 barns/cm3
    Fermion index Fermion index = 0.0030503228
    Boson index = 0.9969496772
    Radioactivity GRapi = 0 (Gamma Ray American Petroleum Institute Units)
    Abswurmbachite is not radioactive

How to Identify Abswurmbachite

Abswurmbachite can be identified in the field by its brownish-black color. It is opaque, with a hardness of 6.5 (approximate to pyrite), and a density of 4.96g/cm3.

This mineral has a metallic lustre, with no cleavage.

Global Distribution

Abswurmbachite can be found on the islands of Greece at Mili, Evvia Island, and Apikia, Andros Island, and the Cyclades Islands.

Occurrence of Abswurmbachite and Useful Mineral Association

Abswurmbachite occurs in very low-grade, high-pressure metamorphic manganese-aluminum-rich quartzites.

It is often associated with minerals such as quartz, tenorite, ardennite, sursassite, rutile, hollandite, shattuckite, clinochlore, and piemontite.

References

http://www.mindat.org/min-9.html

http://rruff.geo.arizona.edu/doclib/hom/abswurmbachite.pdf

http://webmineral.com/data/Abswurmbachite.shtml

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