Editing Bornite (section)

===Structure===
[[File:Bornite by petrographic microscope.jpg|thumb|Microscopic picture of Bornite]]
At temperatures above {{convert|228|C}}, the structure is [[Cubic crystal system|isometric]] with a unit cell that is about 5.50&nbsp;Å on an edge. This structure is based on cubic close-packed [[sulfur]] atoms, with copper and iron atoms randomly distributed into six of the eight [[Tetrahedron|tetrahedral]] sites located in the octants of the cube. With cooling, the Fe and Cu become ordered, so that 5.5&nbsp;Å subcells in which all eight tetrahedral sites are filled alternate with subcells in which only four of the tetrahedral sites are filled; symmetry is reduced to [[Orthorhombic crystal system|orthorhombic]].<ref name=Nesse>Nesse, William D., "Sulfides and Related Minerals" in ''Introduction to Mineralogy,'' New York: Oxford University Press, 2000, p 429</ref>