When viewed under a microscope in plane polarized light, skaergaardite appears to be bright creamy white ( in the presence of bornite or chalcopyrite ) or bright white ( in the presence of digenite or chalcocite ).
12.
Low digenite is isometric, space group Fdm and a = 27.85 ? i . e . the same as the apparent isometric symmetry of the metastable polymorph, Z = 4 for formula Cu 1.8 S.
13.
The supergene sulfide zone is present from about 35 to 65 m in depth and has significant copper enrichment, with predominantly chalcocite, and lesser digenite, covellite, and bornite, along with pyrite, minor pyrrhotite, anglesite, and gangue minerals.
14.
Supergene profiles can be developed above weathered examples of IOCG deposits, as exemplified by the Sossego deposit, Para State, Brazil, where typical oxidised copper minerals are present, e . g .; malachite, cuprite, native copper and minor amounts of digenite and chalcocite.
15.
Associated copper minerals include the sulfides bornite ( Cu 5 FeS 4 ), chalcocite ( Cu 2 S ), covellite ( CuS ), digenite ( Cu 9 S 5 ); carbonates such as malachite and azurite, and rarely oxides such as cuprite ( Cu 2 O ).
16.
This symmetry, however, is due to twinning of fine domains with rhombohedral symmetry, trigonal-3m, point group R-3m, a = 3.92 ? c = 48 ? Z = 15 for formula Cu 1.8 S . Metastable digenite changes with time to stable low temperature digenite or a mixture of anilite Cu 7 S 4 and djurleite Cu 31 S 16.
17.
This symmetry, however, is due to twinning of fine domains with rhombohedral symmetry, trigonal-3m, point group R-3m, a = 3.92 ? c = 48 ? Z = 15 for formula Cu 1.8 S . Metastable digenite changes with time to stable low temperature digenite or a mixture of anilite Cu 7 S 4 and djurleite Cu 31 S 16.
