Editorial Feature

Brochantite – Occurrence, Properties, and Distribution

Brochantite was named after Professor Andre Jean Francois Marie Brochant de Villiers (1772–1840), a French geologist and mineralogist associated with the School of Mines in Paris, France.

Properties of Brochantite

The following are the key properties of brochantite:

  • Cell Data
    • Space group: P21/a
    • a = 13.08
    • b = 9.85
    • c = 6.02
    • β = 103° 22’
    • Z = 4

  • Crystal Data
    • Monoclinic
    • Point group: 2/m
    • Crystals are typically thick prismatic to acicular, elongated along [001] or [010], to 5cm
    • May be flattened [001]
    • In aggregates, druses, crusts, also massive, granular
    • Twinning: On {100}, common, giving a pseudo-orthorhombic appearance
    • X-ray powder pattern: 2.521 (100), 3.90 (85), 2.678 (50), 6.38 (40), 5.36 (40), 3.19 (40), 2.923 (20)

  • Chemical Composition
    Elements Content 1 Content 2
    CuO 70.29 70.35
    SO3 17.54 17.70
    H2O 11.96 11.95
    Total 99.79 100.00

  • Optical Properties
    • Optical class: Biaxial (-)
    • Pleochroism: Slight; in bluish-greens
    • Orientation: Y = b; X ≃ a; Z ≃ c
    • Dispersion: r < v , medium
    • α = 1.728; β = 1.771; γ = 1.800
    • 2V(meas.) = 77(2)°

  • Estimated Properties
    Electron density Bulk density (electron density) = 3.84 g/cm3
    note: Specific gravity of brochantite = 3.98 g/cm3
    Photoelectric PEBrochantite = 25.03 barns/electron
    U=PEBrochantite x ρ electron density = 96.02 barns/cm3
    Fermion index Fermion index = 0.0007035267
    Boson index = 0.9992964733
    Radioactivity
    Brochantite is not radioactive

How to Identify Brochantite

Brochantite can be identified in the field by its color variations, such as green, emerald-green, and black. Its transparent to translucent form has {100} perfect cleavage. This mineral has a vitreous-pearly luster with pale green streak. The fracture on this mineral is brittle-conchoidal, meaning curved shavings or scrapings produced by a knife blade.

The density of brochantite is 3.97 g/cm3 with a hardness of 3.5 to 4 - between a copper penny and fluorite. It is non-fluorescent.

Global Distribution

Brochantite is distributed in the following places:

  • Russia - From the Mednorudyanskoye copper deposit, near Nizhni Tagil, and at Gumeshevsk, south-west of Yekaterinburg (Sverdlovsk), Ural Mountains
  • Romania - At Baita (Rezbanya)
  • Italy - From Rosas and Sa Duchessa, Sardinia
  • Germany - At the Clara mine, near Oberwolfach, Black Forest
  • England - Numerous occurrences in Cornwall, and at Roughton Gill, Cumbria
  • Namibia - From Tsumeb
  • Algeria - At Ain-Barbar, Constantine
  • Australia - At Broken Hill, New South Wales
  • Chile - As at Chuquicamata and Collahuasi, Antofagasta; from Potrerillos, Atacama; and at Challacollo, Tarapaca
  • USA - In Arizona, large crystals from Bisbee, Cochise Co. and at the Mammoth-St. Anthony mine, Tiger, Pinal Co.; in the Mammoth mine, Tintic, Juab Co. Utah; at Bingham, Socorro Co. New Mexico; from the Cerro Gordo mine, Inyo Co. California; in the Douglas Hill and Mason Pass mines, Yerington district, Lyon Co. Nevada

Occurrence of Brochantite and Useful Mineral Association

Brochantite commonly occurs in the oxidized zone of copper deposits, and rarely in an ore. It is formed under low acidity, especially in arid regions.

It is often associated with minerals such as malachite, azurite, cuprite, linarite, caledonite, cerussite, atacamite, cyanotrichite, tenorite, chrysocolla, and iron oxides.

References

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