Brochantite

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Brochantite

Description

A vivid green mineral composed of tribasic copper sulfate. Brochantite was discovered by French grologist, A.J.M Brochant de Villiers. It is a secondary mineral found in oxidized zones of Copper deposits in Arizona, Chile, Mexico, and Russia. The mineral also forms as a bright green corrosion product on copper and Bronze artifacts exposed to Sulfur containing pollution. Brochantite is considered a stable patina, but may indicate pit formation for outdoor leaded bronzes due to the formation of a soluble lead sulfate.

See also Antlerite.

Synonyms and Related Terms

tribasic copper sulfate; Brochantit (Deut.); brochantite (Fr., It.); brocantita (Esp.); brochantiet (Ned.); brochantite (Port.)

FTIR (MFA)

Brochantite.TIF

Raman (MFA)

Brochantite Raman MFA 385.TIF

XRD (MFA)

PIG385.jpg

SEM (MFA)

F385sem.jpg

EDS (MFA)

F385edsbw.jpg


Physical and Chemical Properties

  • Needle-like prisms in orthorhombic crystalline system.
  • Streak = pale green.
  • Luster = vitreous.
  • Perfect cleavage in one direction.
  • Fracture = conchoidal
Composition Cu4SO4(OH)6
Mohs Hardness 3.5 - 4.0
Density 3.9-4.0 g/ml

Resources and Citations

  • Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • Thomas Gregory, The Condensed Chemical Dictionary, Reinhold Publishing, New York, 3rd ed., 1942
  • Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997