The replacement of chrome spinel by chromian valleriite in sulphide-bearing ultramafic rocks in Western Australia |
| |
| Authors: | E H Nickel D R Hudson |
| |
| Institution: | (1) Division of Mineralogy, CSIRO, Perth, W. A., Australia |
| |
| Abstract: | Chromian valleriite occurs as a replacement product of chrome spinel in the Nepean and Perseverance nickel-iron sulphide deposits of Western Australia. Compositions determined for chromian valleriites are variable due to intergrowth with spinel and to substitution of Fe and Ni for Cu. At Perseverance, valleriite, with minor admixed chrome spinel, has a composition expressed by the formula Fe1.18Cu0.81Ni0.01S2.00·2.03Mg0.50Cr0.37Mn0.08Fe0.03Ti0.01Al0.01(OH)2.00]. Nepean valleriites are similarly intergrown with spinel, with the purest chromian valleriites varying in composition from a nickel-poor Fe1.21Cu0.78Ni0.01S2.00·1-46.Mg0.43Cr0.18Mn0.05Fe0.30(OH)2] to Fe1.58Cu0.28Ni0.15S2.00·1.79Mg0.51Cr0.30Fe0.16Ti0.03(OH)2]. Conversion of chrome spinel to valleriite is attributed to addition of Cu and S from the breakdown of chalcopyrite, addition of Mg from serpentinising olivine and limited addition of Ni from the breakdown of pentlandite to mackinawite. These processes are thought to occur as post-metamorphic hydrothermal reactions in nickel sulphide ores that have been subjected to high grade regional metamorphism. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
