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