Figure 7

(a) Reflected plane polarized light photomicrograph of late carbonate vein cross-cutting chalcopyrite, pyrite, and specular hematite in hematite-bearing ore from the Bingham north ore shoot. Note how hematite blades are locally rounded/resorbed by chalcopyrite. Also note how Fe-occurs on vein walls and calcite fills vein center. Silver blades = hematite, pale yellow = pyrite, yellow = chalcopyrite, medium dark rhombs along rim of vein = Fe-carbonate, calcite vein core, black spots in chalcopyrite = holes. Width of field = 2.69 mm.

(b) Combination transmitted and reflected plane-polarized light photomicrograph of late siderite veins cross-cutting pyrite in hematite-bearing ore from the C-bed orebody of the Superior district, Arizona. Siderite veins cut all other assemblages elsewhere in the deposit. Note siderite pseudomorphs after hematite inclusions in pyrite. Buff = siderite, pale yellow = pyrite, white = hole in section. Width of field = 2.69 mm.