Name/Title
Peacock OreEntry/Object ID
2022.9.5Description
Bornite & Chalcopyrite
About Bornite
Formula: Cu5FeS4
Colour: Copper-red to pinchbeck-brown, quickly tarnishing to an iridescent purplish surface.
Lustre: MetallicHardness:3Specific
Gravity: 5.06 - 5.09
Crystal System: Orthorhombic
Name: Originally included with kupferkies in 1725 by Johann Friedrich Henckel. Later assigned various multi-word Latin names by Johan Gottschalk Wallerius in 1747 and variously further translated including "purple copper ore" and "variegated copper ore" in 1802 by Rene Just Haüy. Also called as buntkupfererz by Abraham Gottlieb Werner in 1791. Named "phillipsite" in 1832 by Wilhelm Sulpice Beudant. Renamed as bornite in 1845 by Wilhelm Karl von Haidinger in honor of Ignaz von Born (1742-1791), Austrian mineralogist and invertebrate zoologist.Type Locality:ⓘ Jáchymov, Karlovy Vary District, Karlovy Vary Region, Czech Republic
An important copper ore, typically found as massive or disseminated metallic grains and patches in sulphide ore deposits; relatively rare as good euhedral crystals.
It has a copper-reddish colour on fresh exposures which quickly tarnishes to a pinkish grey, through to an iridescent purple, crimson or blue and eventually black, after exposure to air and moisture, due to formation of very thin coatings of more oxidised minerals.
It may be confused with other iridescent minerals, especially iridescently tarnished chalcopyrite, both often termed “peacock ore” when exhibiting such a tarnish.
Bornite is a copper(I) iron sulphide, with Fe likely predominantly being trivalent, although with some charge transfer likely possible (Goh et al. 2006). Substantial variation in the relative amounts of copper and iron occurs and solid solution extends towards chalcopyrite (CuFeS2) and digenite (Cu9S5). In the Zechstein deposits of Poland there are two copper-deficient varieties defined: half-bornite and quatr-bornite, about 50 and 75% deficient in iron respectively.
In terms of crystallochemistry, at temperatures above 228 °C, the structure is isometric with copper and iron atoms randomly distributed but with cooling, the Fe and Cu become ordered, and symmetry is reduced to orthorhombic.
About Chalcopyrite
Formula:CuFeS2
Colour:Brass yellow, often with an iridescent tarnish.
Lustre:Metallic
Hardness:3½ - 4
Specific Gravity:4.1 - 4.3
Crystal System:Tetragonal
Member of:Chalcopyrite
GroupName:Named in 1725 by Johann Friedrich Henckel from the Greek "chalkos", copper, and "pyrites", strike fire.
Chalcopyrite Group. Chalcopyrite-Eskebornite Series.
A major ore of copper. Common in sulfide veins and disseminated in igneous rocks.
Weathering may lead to the formation of malachite, azurite, brochantite, langite and numerous other secondary copper minerals.
A Zn-rich variety is known from Atlantis II Deep (see zincian chalcopyrite). Also, the Mid-Atlantic-ridge isocubanite may transform to chalcopyrite and UM1994-22-S:CuFe (Cu1-xFe3+xS4 (Wintenberger et al., 1994).Location
Location
Display Case
FS-11Room
Frieda Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Curtis GardnerDate
December 27, 2023Notes
Added current location