Gordaite - Occurrence, Properties, and Distribution

Gordaite is a trigonal-pyramidal mineral containing zinc, sulfur, sodium, oxygen, hydrogen, and chlorine. It was first discovered in 1996 in the San Francisco mine, Sierra Gorda District, Tocopilla Province in the Antofagasta Region of Chile. The mineral was named after its place of discovery.

Properties of Gordaite

The following are the key properties of Gordaite:

  • Cell Data
    • Space Group: P3
    • a = 8.3556(3)
    • c = 13.025(1)
    • Z = 2

  • Crystal Data
    • Hexagonal
    • Point Group: 3
    • As thin tabular flakes, with hexagonal outline, or as blades, to 2cm; in rosette-like aggregates
    • X-ray Powder Pattern: 12.95 (100), 6.501 (23),4.339 (15), 3.258 (14),2.967 (10), 2.523 (6),2.676 (5)

  • Chemical Composition
    Elements Content 1 Content 2
    SO3 15.33 12.79
    ZnO 52.85 51.99
    Na2O 9.15 4.95
    CI 6.46 5.66
    H2O 12.33 25.89
    -O = Cl2 1.46 1.28
    Total 94.66 100.00

  • Optical Properties
    • Optical Class: Uniaxial (-)
    • ω = 1.5607(8)
    • ε = 1.5382(4)

  • Estimated Properties
    Electron density Bulk density (electron density)=2.60 g/cm3
    note: Specific gravity of Gordaite =2.63 g/cm3
    Photoelectric PEGordaite = 20.99 barns/electron
    U= PEGordaite x ρElectron density= 54.60 barns/cm3
    Fermion index Fermion index = 0.01
    Boson index = 0.99
    Gordaite is not radioactive

How to Identify Gordaite

Gordaite is usually colorless or white. It has perfect cleavage, vitreous luster and white streak. It forms uniformly indistinguishable crystals of large masses. The density of gordaite is 2.6 g/cm3, and its hardness is 2.5.

Global Distribution

Gordaite is distributed in the following places:

  • San Francisco mine, 2km west of the Sierra Gorda railway station, Sierra Gorda district, Antofagasta, Chile
  • Juan de Fuca Ridge, southwest of Vancouver Island, Canada
  • Near Helbra, Mansfeld region, Saxony-Anhalt, Germany
  • Kamariza mine, Laurium, Greece

Occurrence of Gordaite and Useful Mineral Association

Gordaite occurs in the oxidized portions of a Cu-Zn sulfide deposit on weathered mine dumps, and outside oxidized portions of a sea floor chimney, which is formed of a mixture of hydrothermal fluids and sea water.

The minerals that are closely associated with gordaite include iron hydroxides, sulfur, pyrrhotite, pyrite, barite, sphalerite, chlorian bromargyrite, anglesite, connellite, quartz, christelite, hemimorphite, and zincian paratacamite.


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