Friday, 18 March 2011

Bornite, peacock ore and chalcopyrite ~

Bornite and chalcopyrite are closely related but they are not the same thing: 
  • The chemical formula for bornite is Cu5FeS4
  • The chemical formula for chalcopyrite is CuFeS2
  • In comparison the formula for pyrite is a little more straight forward! It is: FeS2
Up to this point I have avoided getting too technical about this sort of thing, but there seems to be a lot of confusion between the two in web articles and this is one level of certainty I do have!  

Bornite and chalcopyrite are both sources of copper, with the latter being the most significant one.

The specimens shown here match Wikipedia's description of bornite, which is also known as peacock ore due to its colourful tarnish.

In the Wikipedia article about chalcopyrite it is noted that it is often confused with pyrite, and describes it, among other things, as "a darker yellow in colour, with a greenish tinge and diagnostic greasy lustre".

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