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Bornite with Quartz Veins

The Mineral bornite




"Peacock Ore", which is sold to many amateur mineral collectors and often labeled as a variety of Bornite, is usually Chalcopyrite that is treated with acid to produce a stronger iridescent tarnish.
Chemical Formula Cu5FeS4
Composition Copper iron sulfide
Color Copper-red to yellowish brown on fresh surfaces. Quickly tarnishes to a multicolored purple, blue, and red.
Streak Dark gray to black
Hardness 3
Crystal System Orthorhombic
Crystal Forms
and Aggregates
Bornite forms as isometric crystals at high temperatures, but when it cools down to normal temperatures it crystallizes in the orthorhombic system. However, the crystals retain their original isometric crystals. Crystals are rare, and are in cubic or dodecahedral form. Octahedral shaped crystals are extremely rare. Bornite occurs mostly massive, as well as in groups of tiny crystals and globular.
Transparency Opaque
Specific Gravity 4.9 - 5.3
Luster Metallic
Cleavage Indiscernible
Fracture Conchoidal
Tenacity Brittle
Other ID Marks Tarnishes to an iridescent purple, blue, and red.
In Group Sulfides; Simple Sulfides
Striking Features Tarnish, low hardness, and association with copper ores.
Environment In copper ore veins, both as a primary and secondary mineral. Mainly in hydrothermal metamorphic rocks, in mesothermal veins, in hydrothermal replacement deposits, and in igneous intrusions and dikes.
Rock Type Igneous, Metamorphic
Popularity (1-4) 2
Prevalence (1-3) 1
Demand (1-3) 2

Bornite ON EBAY
OTHER NAMES
Blushing Copper
Erubescite
Peacock Copper
Purple Copper Ore
Variegated Copper

VARIETIES
 -  Term used to describe Chalcopyrite or Bornite with a colorful iridescent tarnish effect, which is usually artificially enhanced with acid. Most Peacock Ore is sold as a variety of Bornite, when in fact most Peacock Ore is actually Chalcopyrite.

USES
Bornite is a common copper bearing mineral, and is used as an ore of copper when found in copper deposits.

NOTEWORTHY LOCALITIES
The largest and most distinct crystals of Bornite have come from Dzhezkazgan, Kazakhstan. Good crystals also come from Shaba, Congo (Zaire); and from the Mangula Mine in Mhangura, Zimbabwe. The province of Cornwall, England has produced many Bornite specimens, including some crystallized examples (especially in the Carn Brea Mine).  Nice crystals as well as massive form come from San Martin, Zacatecas, Mexico.

Large quantities of Bornite, mostly in massive form, have been extracted from the Arizona copper mines, particularly the Magma mine in Superior, Pinal Co.; and the Copper Queen Mine in Bisbee, Cochise Co. Small crystals also come from Butte, Silver Bow Co., Montana, where much massive material is also found. Small crystals were also once found at the copper mine at Bristol, Hartford Co., Connecticut.

Large amounts of Bornite have come from the Evergreen mine near Apex, Gilpin Co., Colorado, and the Flambeau Mine, Ladysmith, Rusk Co., Wisconsin. It also has been found in the White Pine mine, Ontonagan Co., Michigan; the French Creek mine, St. Peters, Chester Co., Pennsylvania; Luzerne Co., Pennsylvania; and the Chimney Rock Quarry, Bound Brook, New Jersey.

In Canada, occurrences include the Marble Bay mine, Texada Island, British Columbia, and the Acton mine, Bagot Co., Quebec.

COMMON MINERAL ASSOCIATIONS
Quartz, Pyrite, Calcite, Barite, Galena, Chalcopyrite, Chalcocite, Magnetite

DISTINGUISHING SIMILAR MINERALS
Chalcopyrite - different crystal form, usually lighter in color, less tarnish
Pyrrhotite - harder (3½ - 4½), attracted to magnetic fields, no tarnish
Nickeline - harder (5 - 5½), heavier (S.G. = 7.8), no tarnish


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