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Dyscrasite - Occurrence, Properties, and Distribution

Dyscrasite is a silver antimonide mineral that was first described in 1797 in the Wenzel Mine, Black Forest, Germany. The mineral was named after the Greek word δυσκράσις, meaning 'bad alloy’.

Properties of Dyscrasite

The following are the key properties of Dyscrasite:

  • Cell Data
    • Space Group: Pmm2
    • a = 3.008
    • b = 4.828
    • c = 5.214
    • Z = 1

  • Crystal Data
    • Orthorhombic
    • Point Group: mm2
    • Pyramidal crystals, to 5cm, also cylindrical, prismatic to platy, striated; granular, foliated or massive
    • Twinning: On {110}, giving pseudohexagonal forms and V-shapes
    • X-ray Powder Pattern: 2.29 (100), 2.42 (40), 1.370 (40), 2.61 (30), 1.771 (30), 1.506 (30), 1.278 (30)

  • Chemical Composition
    Elements Content 1 Content 2 Content 3
    Ag 75.41 73.1 72.66
    Sb 24.37 26.1 27.34
    Total 99.78 99.2 100

  • Optical Properties
    • Pleochroism: Very weak
    • Anisotropism: Weak

  • Estimated Properties
    Electron density Bulk density (electron density) = 8.42 g/cm3
    note: Specific gravity of Dyscrasite = 9.76 g/cm3
    Photoelectric PEDyscrasite = 285.26 barns/electron
    U = PEDyscrasite x ρElectron density = 2400.56 barns/cm3
    Fermion index Fermion index = 0
    Boson index = 1
    Radioactivity
    Dyscrasite is not radioactive

How to Identify Dyscrasite

Dyscrasite occurs in black, gray, yellow, or silver-white colors. It is a non-fluorescent, non-magnetic mineral, having a silver-white streak and metallic luster. It produces curved shavings or scrapings, and can be formed as granular or pseudo-hexagonal crystals.

The relative hardness of dyscrasite ranges from 3.5 to 4, and its average density is 9.69.

Global Distribution

Dyscrasite is distributed in the following places:

  • Black Forest, from Wenzelgang, near Wolfach and Wittichen, Germany
  • St. Andreasberg, Harz Mountains
  • Wasserfall, about 20km north-west of Belfort, Haute-Saone, France
  • Sainte-Marie-aux-Mines, Haut-Rhin
  • Hiendelaencina, Guadalajara Province, Spain
  • Pribram, Czech Republic
  • Langsjon, Sweden
  • Kongsberg and Sulitjelma, Norway
  • Consols mine, Broken Hill, New South Wales, Australia
  • Chanarcillo, south of Copiapo, Atacama, Chile
  • Colquechaca, Bolivia
  • Highbridge mine, Belmont district, Nye Co. Nevada, USA
  • Cobalt, Ontario, Canada
  • Tanco pegmatite, Bernic Lake, Manitoba
  • Ilimaussaq intrusion, southern Greenland
  • Yuzhnyi tin deposit, Tetukhe region, southern Maritime Territory, Russia
  • Aktepe Ag–As deposits, near Tashkent, Uzbekistan
  • Shkol’noe deposit, Kurama Ridge, Tadjikistan
  • Rampura Agucha Zn–Pb–Ag deposit, Rajasthan, India

Occurrence of Dyscrasite and Useful Mineral Association

Dyscrasite occurs in hydrothermal veins, with other silver minerals, as both a primary and secondary mineral.

It is closely associated with barite, calcite, galena, allemontite, tetrahedrite, stromeyerite, acanthite, and pyrargyrite.

References

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