 |
Chemical Formula | CuFeS2 | |||||
|
Composition | Copper iron sulfide | |||||
|
Color | Brass yellow to golden yellow. Tarnishes purple, blue, and red. | |||||
|
Streak | Black with a slightly green tinge | |||||
|
Hardness | 3½ - 4 | |||||
|
Crystal Forms and Aggregates |
(Tetragonal) Crystals resemble tetrahedrons and octahedrons, but they are slightly asymmetrical and therefore must be categorized in the tetragonal system. Also occurs massive, grainy, reniform, and as groups of small, distorted crystals. Crystals are commonly striated in different directions on different crystal faces. | |||||
|
Transparency | Opaque | |||||
|
Specific Gravity | 4.1 - 4.3 | |||||
|
Luster | Metallic | |||||
|
Cleavage | Indiscernible | |||||
|
Fracture | Uneven | |||||
|
Tenacity | Brittle | |||||
|
Other ID Marks | Tarnishes to an iridescent purple, blue, and red | |||||
|
Other Names |  Copper Pyrites, Yellow
Copper, Cupropyrite"Peacock Ore" is a term given to tarnished, iridescent Bornite, but is usually Chalcopyrite with a heavy tarnish produced by acid. |
|||||
|
In Group | Sulfides ; Simple sulfides | |||||
|
Uses | Chalcopyrite is the chief ore
of copper. "Peacock Ore" which is sold to many amateur mineral collectors and thought to be Bornite usually is Chalcopyrite that is treated with acid to produce a greater tarnish. Chalcopyrite is sometimes polished into beads and pendants as cheap jewelry. |
|||||
|
Striking Features | Low hardness, crystal form, iridescent tarnish, and brittleness | |||||
|
Complex Tests | Soluble in nitric acid, tingeing the solution blue | |||||
|
Popularity (1-4) | 2 | |||||
|
Prevalence (1-3) | 1 | |||||
|
Demand (1-3) | 1 | |||||
|
Distinguishing Similar Minerals |
Pyrite and Marcasite - paler color, harder (6 - 6½) Gold - nonbrittle, much heavier (15.5 - 19.3) Bornite - different crystal form, usually darker in color, more tarnish |
|||||
|
Commonly Occurs With |
Pyrite, Sphalerite, Bornite, Chalcocite, Barite, Fluorite, Quartz, Calcite | |||||
|
Noteworthy Localities |
Chalcopyrite is a fairly common mineral, and
therefore only the finest of localities will be
mentioned. Large, well shaped crystals occur in numerous
places in Cornwall, England, as well as Akita, Ugo, and
Tochigi Perfectures, Japan. Many fine crystals occur in
the northern section of Mexico; certain occurrences are
La Bufa, Chihuahua ; Charcas, San Luis Potosi; and the
Noche Buena mine, near Mazapil, Zacatecas. The French Creek Mine in Chester Co., Pennsylvania has produced huge crystals, many distorted and highly tarnished. Large amounts of Chalcopyrite occur with Sphalerite, Galena, and Marcasite in the Joplin district of Missouri, Oklahoma, and Kansas. |
|||||
|
Picture Icon Links |
|
|||||
|
Picture Links | 1. Curved tetrahedral crystals 2. Chalcopyrite with Hematite on Calcite |
