Home » Minerals » Chalcopyrite

Chalcopyrite

The world's most important ore of copper for at least five thousand years.

auriferous chalcopyrite

Auriferous Chalcopyrite: A specimen of chalcopyrite with pyrrhotite from the Rouyn District, Quebec, Canada. Some chalcopyrite contains enough gold or silver that it can be an ore of those metals without considering the copper content. This specimen is about ten centimeters across.

What is Chalcopyrite?

Chalcopyrite is a brass-yellow mineral with a chemical composition of CuFeS2. It occurs in most sulfide mineral deposits throughout the world and has been the most important ore of copper for thousands of years.

The surface of chalcopyrite looses its metallic luster and brass-yellow color upon weathering. It tarnishes to a dull, gray-green color, but in the presence of acids the tarnish can develop a red, to blue to purple iridescence.

The iridescent colors of weathered chalcopyrite attract attention. Some souvenir shops sell chalcopyrite that has been treated with acid as "peacock ore." But, "peacock ore" is a more appropriate name for the mineral bornite.



Physical Properties of Chalcopyrite

Chemical Classification Sulfide.
Color Brass yellow. Tarnishes to gray green, sometimes iridescent.
Streak Greenish black.
Luster Metallic.
Diaphaneity Opaque.
Cleavage Poor.
Mohs Hardness 3.5 to 4
Specific Gravity 4.1 to 4.3
Diagnostic Properties Color, greenish streak, softer than pyrite, brittle.
Chemical Composition Copper iron sulfide, CuFeS2.
Crystal System Tetragonal.
Uses The most important ore of copper for thousands of years..

crystals of chalcopyrite on dolomite

Chalcopyrite on Dolomite: Tetragonal crystals of chalcopyrite on dolomite from Baxter Springs, Kansas. This specimen is about 10 centimeters across.

Physical Properties of Chalcopyrite

The most obvious physical properties of chalcopyrite are its brassy yellow color, metallic luster, and high specific gravity. These give it a similar appearance to pyrite and gold. Distinguishing these minerals is easy. Gold is soft, has a yellow streak and has a much higher specific gravity. Chalcopyrite is brittle and has a greenish gray streak. Pyrite is hard enough that it can not be scratched with a nail but chalcopyrite is easily scratched with a nail.

The name "fools gold" is most often associated with pyrite because it is more common and more often confused with gold. Chalcopyrite is also confused with gold and the name "fools gold" is also applied and appropriate.



chalcopyrite

Chalcopyrite: Chalcopyrite from Ajo, Arizona. Specimen is approximately 10 centimeters across.




chalcopyrite

Chalcopyrite: Specimen of chalcopyrite from Rouyn District, Quebec, Canada. Specimen is approximately 10 centimeters across.

Geologic Occurrence of Chalcopyrite

Chalcopyrite forms under a variety of conditions. Some is primary, crystallizing from melts as accessory minerals in igneous rocks. Some forms by magmatic segregation and is in the stratified rocks of a magma chamber. Some occurs in pegmatite dikes and contact metamorphic rocks. Some is disseminated through schist and gneiss. Many volcanogenic massive sulfide deposits containing chalcopyrite are known.

The most significant chalcopyrite deposits to be mined are hydrothermal in origin. In these, some chalcopyrite occurs in veins and some replaces country rock. Associated ore minerals include pyrite, sphalerite, bornite, galena and chalcocite.

Chalcopyrite serves as the copper source for many secondary mineral deposits. Copper is removed from chalcopyrite by weathering or solution, transported a short distance, then redeposited as secondary sulfide, oxide or carbonate minerals. Many malachite, azurite, covellite, chalcocite and cuprite deposits contain this secondary copper.

Uses of Chalcopyrite

The only important use of chalcopyrite is as an ore of copper, but this single use should not be understated. Chalcopyrite has been the primary ore of copper since smelting began over five thousand years ago.

Some chalcopyrite ores contain significant amounts of zinc substituting for iron. Others contain enough silver or gold that the precious metal content more than pays the costs of mining.

More Minerals
  Fluorescent Minerals
  Minerals
  Quartz
  The Streak Test
  Diamond
  Diopside
  Hand Lens
  Topaz

More From Geology.com:


Labradorite
Labradorite: A feldspar that produces bright flashes of iridescent colors.
Hand Lens
Hand Lens A 10-power folding magnifier in a metal case. A frequently used lab and field tool.
city satellite images
What City is This? Can you recognize United States cities from satellite images?
Asteroid Impact Map
Asteroid Impact Map: Explore fifty of the most obvious asteroid impact craters on Earth.
Uses of granite
Uses of Granite: The rock used everywhere from the kitchen to the facing stone of skyscrapers.
Rhodonite
Rhodonite - a manganese silicate used as a minor ore of manganese and as a gemstone.
lightning map
Lightning Strikes Map - A NASA map showing the worldwide distribution of lightning activity.
Kyanite
Kyanite is a metamorphic mineral that sometimes has a gemmy transparent blue color.