Aurichalcite – Occurrence, Properties, and Distribution

Aurichalcite was named after the Latin word for golden copper or brass, in allusion to the copper and zinc content of the mineral.

Properties of Aurichalcite

The following are the key properties of aurichalcite:

  • Cell Data
    • Space group: P21/m
    • a = 13.82(2)
    • b = 6.419(3)
    • c = 5.29(3)
    • β = 101.04(2)°
    • Z = 2
  • Crystal Data
    • Monoclinic, pseudo-orthorhombic by twinning.
    • Point group: 2/m.
    • As acicular to lath-like crystals with prominent {010}, commonly striated || [001], with wedge-like terminations, to 3 cm.
    • In tufted divergent sprays or spherical aggregates.
    • Twinning : Observed in X-ray patterns.
    • X-ray powder pattern: 6.78 (10), 2.61 (8), 3.68 (7), 2.89 (4), 2.72 (4), 1.827 (4), 1.656 (4).
  • Chemical Composition
    Elements Content 1
    ZnO 54.01
    CuO 19.87
    CO2 16.22
    H2O 9.93
    CaO 0.36
    Total 100.39
  • Optical Properties
    • Optical class: Biaxial (-)
    • Pleochroism: Weak; X = colorless; Y = Z = blue-green.
    • Orientation: X = b; Y ≃ a; Z ≃ c.
    • Dispersion: r < v, strong
    • α = 1.654–1.661; β = 1.740–1.749; γ = 1.743–1.756
    • 2V(meas.) = Very small.
  • Estimated Properties
    Electron density Bulk density (electron density) = 3.62 g/cm3
    Note: Specific gravity of aurichalcite = 3.77 g/cm3
    Photoelectric PEAurichalcite = 28.76 barns/electron
    U = PEAurichalcite x ρ electron density= 104.21 barns/cm3
    Fermion index Fermion index = 0.01
    Boson index = 0.99

    Radioactivity

    Aurichalcite is not radioactive

How to Identify Aurichalcite

Aurichalcite can be identified in the field by its color variations such as pale green, sky blue, and greenish blue. Its transparent and non-fluorescent form has {010} perfect cleavage. This mineral has a pearly luster with a light blue streak. The fracture on this mineral is uneven. The density of aurichalcite is 3.64 - 3.9 g/cm3 with a hardness of 2 - approximate to gypsum.

Global Distribution

Aurichalcite is distributed in the following places:

  • Russia - From the Loktevskii mine, upper Loktevka River, west Altai Mountains.
  • Italy - At Monteponi, and in the Rosas mine, Sulcis, Sardinia.
  • From Laurium, Greece. At Chessy, near Lyon, Rhone, France.
  • USA -In Arizona, fine examples from Bisbee, Cochise Co., in the Silver.
  • Hill mine, Pima Co., and at the 79 mine, Gila Co.; from Cerro Gordo, Inyo Co., California; at the Kelly and Graphic mines, Magdalena, Socorro Co., New Mexico. In Utah, from the Tintic district, Juab Co., at the Hidden Treasure mine, Tooele Co., in the Apex mine, near St. George, Washington Co., and from Big Cottonwood Canyon, Salt Lake Co.; at Leadville, Lake Co., Colorado.
  • Mexico - rich specimens from the Ojuela mine, Mapimý, Durango.
  • Iran - At the Tchah Khuni mine, Anarak district.
  • Namibia- From Tsumeb.
  • Zaire - At Kipushi, 28 km southwest of Lubumbashi, Katanga Province, Congo (Shaba Province).

Occurrence of Aurichalcite and Useful Mineral Association

Aurichalcite occurs in the oxidized zones of copper and zinc deposits. It is often associated with minerals such rosasite, azurite, hemimorphite, hydrozincite, smithsonite, and malachite.

References

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