Please use this identifier to cite or link to this item:
https://hdl.handle.net/2440/99925
Citations | ||
Scopus | Web of Science® | Altmetric |
---|---|---|
?
|
?
|
Type: | Journal article |
Title: | The replacement of chalcopyrite by bornite under hydrothermal conditions |
Author: | Zhao, J. Brugger, J. Ngothai, Y. Pring, A. |
Citation: | American Mineralogist: an international journal of earth and planetary materials, 2014; 99(11-12):2389-2397 |
Publisher: | Mineralogical Society of America |
Issue Date: | 2014 |
ISSN: | 0003-004X 1945-3027 |
Statement of Responsibility: | Jing Zhao, Joël Brugger, Yung Ngothai, and Allan Pring |
Abstract: | We report the replacement of chalcopyrite by bornite under hydrothermal conditions in solutions containing Cu(I) and hydrosulfide over the temperature range 200–320°C at autogenous pressures. Chalcopyrite was replaced by bornite under all studied conditions. The reaction proceeds via an interface coupled dissolution-reprecipitation (ICDR) mechanism and via additional overgrowth of bornite from the bulk solution. Initially, the reaction is fast and results in a bornite rim of homogeneous thickness. Reaction rates then slow down, probably reflecting healing of the porosity, and the reaction proceeds predominantly along twin boundaries of the chalcopyrite. The composition of the bornite product is generally Cu-rich, corresponding to the bornite-digenite(Cu5FeS4-Cu9S5; Bn-Dg) solid solution (bdss). The Cu and Fe contents were controlled principally by temperature, with solution pH having only a small effect. The percentage of Cu in bdss decreased and the percentage of Fe increased with increasing reaction temperature: at 200°C a composition of Bn47Dg53 was obtained; at 300°C the composition was Bn90Dg10 and at 320°C it was near-stoichiometric bornite. The influence of temperature rather than solution chemistry on the composition of bdss, as well as the homogeneity of the bornite product grown both via replacement of chalcopyrite and from the bulk solution as overgrowth, are interpreted to reflect buffering of the bornite activity in bdss via solids (e.g., reaction chalcopyrite + 2 chalcocite = bornite). Only the end-member compositions of the bdss are found in nature, indicating that the products obtained are metastable, and illustrating the importance of reaction mechanism for controlling the chemistry of the mineral product. The unique features of the chalcopyrite to bornite reaction investigated here are related to interaction between a solution controlled ICDR reaction with solid-state diffusion processes driving porosity healing. |
Keywords: | chalcopyrite; bornite; mineral replacement reaction; diffusion; hydrothermal; bornite-digenite solid solution |
Rights: | © 2014 Mineralogical Society of America |
DOI: | 10.2138/am-2014-4825 |
Grant ID: | http://purl.org/au-research/grants/arc/DP0880884 http://purl.org/au-research/grants/arc/DP1095069 |
Published version: | http://dx.doi.org/10.2138/am-2014-4825 |
Appears in Collections: | Aurora harvest 7 Earth and Environmental Sciences publications |
Files in This Item:
There are no files associated with this item.
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.