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.

FTIR (MFA)

Brochantite.TIF

Raman (MFA)

Brochantite Raman MFA 385.TIF

XRD (MFA)

PIG385.jpg

SEM (MFA)

F385sem.jpg

EDS (MFA)

F385edsbw.jpg

Synonyms and Related Terms

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

Physical and Chemical Properties

  • Composition = Cu4SO4(OH)6
  • Mohs Hardness = 3.5 - 4.0
  • Density = 3.9-4.0 g/ml
  • Ref. Index = 1.771 - 1.800
  • Birefringence = 0.072
  • Needle-like prisms in orthorhombic crystalline system.
  • Streak = pale green.
  • Luster = vitreous.
  • Perfect cleavage in one direction.
  • Fracture = conchoidal

Resources and Citations

  • Mineralogy Database: Brochantite
  • 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
  • Wikipedia: Brochantite (Accessed Sept. 2, 2005 and March 2025)