Figure F29. Characteristic sulfide assemblages (reflected light). A. Euhedral pyrite (Py) in serpentine after olivine (Thin Section 120; Sample 345-U1415P-10R-1, 60–62 cm). B. Chalcopyrite (Ccp) and pyrite intergrown within plagioclase (Thin Section 99; Sample 345-U1415P-4G-1, 41–43 cm). Silicate gangue appears dark gray. C. Heazlewoodite (Hz) replacing pentlandite (Pn) at the grain boundary and along cleavage plane and mantled by magnetite (Mt) in talc after olivine (Thin Section 112; Sample 345-U1415P-7R-1, 60–62 cm). Silicate gangue appears dark gray. D. Magnetite surrounding pyrohotite (Po)-pentlandite intergrowth in serpentine after olivine (Thin Section 128; Sample 345-U1415P-14R-1, 50–52 cm). Pentlandite is altered to pyrite(?) or chalcopyrite along the grain boundary and where the pentlandite was sheared, forming sigmoidal replacements. Magnetite appears ragged on grain boundaries suggesting dissolution. Magnetite stringers are deformed and appear sheared. Serpentine gangue appears dark gray.
Previous | Close | Next | Top of page