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Gold in Sulphide Minerals and Ore Deposits October 2004 Issue 83 GOLD IN SULPHIDE MINERALS AND ORE DEPOSITS Stephen E. Kesler gold, and suggest geologic environ- parts per million gold, much less than Department of Geological Sciences ments that might be favorable for as the limits indicated by the experi- University of Michigan yet undiscovered deposits. ments, indicating that much of the Ann Arbor, MI USA 48109 gold probably exsolved as the deposits Gold in Porphyry Copper Deposits cooled. Introduction Evidence that porphyry copper Just what proportion of the gold A large part of world gold produc- deposits contain visible gold is pro- was originally in solid solution in por- tion comes from porphyry copper- vided by the artisanal mines that ex- phyry copper deposits depends on the gold and Carlin-type deposits in which ploit the upper part of some deposits temperature at which the Cu-Fe sul- the metal is rarely seen. As a result, we in developing countries (Figure 1). phides were deposited. Figure 2 shows have limited information on the min- This gold, which is rarely seen by Cu and Au grades for porphyry cop- eralogical form in which gold was pre- modern miners and must be recovered per deposits along with lines indicating cipitated from solution, and this limits by special gravity circuits, is present the maximum amount of gold that our ability to understand the geochem- largely as micrometre-size grains of could have been deposited in bornite istry of gold during formation of these electrum that are concentrated at and and chalcopyrite at 700, 550 and deposits. A common solution to this near the margins of bornite and chal- 400°C. According to these relations, if quandary has been to assume that gold copyrite (Baldwin et al., 1978; Cuddy in porphyry copper and Carlin-type and Kesler, 1982; Tarkian and Koop- deposits was precipitated as native mann, 1995; Ballantyne et al., 1997; gold or electrum, just as it was in Rubin and Kyle, 1997). The close as- many greenstone and epithermal gold sociation of bornite and chalcopyrite deposits where visible gold is much with gold suggests that it was depos- more common (Cooke and Simmons, ited in solid solution in the Cu-Fe sul- 2000; Hagemann and Cassidy, 2000). phides. Growing information on the ac- Experiments in the Cu-Fe-S-Au tual mineralogical form of gold sug- system show that Cu-Fe sulphides can gests that this assumption is not al- incorporate a large amount of gold in ways correct and that gold in many solid solution (Simon et al., 2000). At deposits is largely in solid solution in any temperature, bornite hosts about other sulphide minerals. This more an order of magnitude more gold than accurate mineralogical information chalcopyrite. At 700°C, the highest provides insights into the reasons that temperature for which data are avail- porphyry copper and Carlin-type de- able, bornite can host 700 ppm gold; posits contain such large amounts of maximum gold contents drop rapidly with decreasing temperature but still amount to almost 10 ppm at 400°C. Inside this issue: The difference in gold-hosting capac- Editor’s Message 3 ity of bornite and chalcopyrite is di- Figure 1. View of the Tiogdan zone at Unesco Heritage Site—Falun Cu 10 rectly related to their copper contents, the Kingking porphyry copper deposit, which are about 64 and 34%, respec- Career Opportunity 12 Philippines, showing extensive artisanal tively (Kesler et al., 2002). SIMS analy- mine workings to recover gold. REE Short Course Report 13 ses of bornite and chalcopyrite in por- (Continued on page 4) phyry copper ores contain only a few Calendar of Events 18 2003-2004 MINERAL DEPOSITS DIVISION EXECUTIVE LIST MDD Goals and Objectives Chairperson: Hendrik Falck The Gangue is published quarterly by the Min- C.S. Lord Northern Geoscience Centre, Box 1500, 4601-B, 52 Avenue, Yellow- eral Deposits Division of GAC and is distrib- knife, NT, X1A 2R3; Tel: (867) 669-2636; Fax: (867) 669-2725 uted to its members. The Mineral Deposits Divi- Eemail: [email protected] sion of the Geological Association of Canada is Canada’s foremost society for promoting the Past Chairperson: Moira Smith study of mineral deposits by supporting local TECK COMINCO Limited, #600 - 200 Burrard Street and national meetings, symposia, short courses Vancouver, BC V6C 3L9; Tel: (604) 640-5373; Fax: (604) 685-3069 and field trips. We sponsor the publication of Email: [email protected] research relating to ore deposits and metallog- eny, and recognize the contributions of out- Vice Chairperson: Jan Peter standing Canadian economic geologists by Geological Survey of Canada, 601 Booth Street, Ottawa, ON, K1A 0E8; Tel: (613) annually awarding the Duncan Derry and Wil- 992-2376; Fax: (613) 996-3726 liam Harvey Gross medals and the Julian Boldy Email: [email protected] Certificate. Publication Schedule: Secretary: ‘Lyn Anglin Geological Survey of Canada, 101 - 605 Robson Street, Rm. 1401, Vancouver, SUBMISSION DATE BC V6B 5J3; Tel: (604) 666-2562; Fax: (604) 666-1124 December 15 January Email: [email protected] March 15 April June 15 July Treasurer: Jason Dunning September 15 October Expatriate Resources, Suite 475, 701 Howe Street, Vancouver, BC V6C 2B3; Tel: (604) 682-5474, ext. 225; Fax (604) 682-5404 Email: [email protected] Information for contributors: The objective of this newsletter is primarily to Publications: Dirk Tempelman-Kluit provide a forum for members and other profes- Tempelman-Kluit Consulting, 4697 West 4th Avenue, Vancouver, BC V6R 1R6; sionals to voice new ideas, describe interesting Tel: (604) 224-5582; Fax: (604) 224-6903 mineral occurrences or expound on deposit Email: [email protected] models. Articles on ore deposits, deposit mod- els, news events, field trips, book reviews, con- Professional Development – Field Trips: Dani Alldrick ferences, reprints of presentations to compa- BC Geological Survey, 5 - 1810 Blanshard Street, Victoria, BC V8T 4J1; nies, mining groups or conferences, or other Tel: (250) 952-0412; Fax: (250) 952-0381 material which may be of interest to the eco- Email: [email protected] nomic geology community are welcome. Manu- scripts should be submitted by email in WP or Short Course Coordinator: Steve Piercey WORD format. A printed version should be Mineral Exploration Research Centre, Dept. of Earth Sciences, Laurentian Univer- mailed or FAXed. Illustrations should be cam- sity, Ramsey Lake Road, Sudbury, ON P3E 2C6; Tel: (705) 675-1151 ext. 2364; era-ready (ideally as CDR digital files); photos Fax: (705) 675-4898 should be of good quality. Short items dealing Email: [email protected] with news events or meetings can be submitted by FAX, postal mail or email. Contributions may Medals Committee and Website Manager: Dan Marshall be edited for clarity or brevity. Dept. of Earth Sciences, Simon Fraser University, Vancouver, BC Tel: (604) 291-5474; Fax: (604) 291-4198 For Information & Submissions: Email: [email protected] Kay Thorne—THE GANGUE NB DNR-Minerals PO Box 6000, Room 150 Check out the updated Fredericton, NB E3B 5H1 Email: [email protected] Tel: (506) 444-2309 MDD Website: Fax: (506) 453-3671 http://mdd.harbour.com/ October 2004 – Gangue No. 83 2 MDD DIRECTORS Message from the Editor • Suzanne Paradis (2002-2005) Natural Resources Canada, 9860 West Saanich Road, Room 4718, Sidney, BC, V8L 4B2; Tel: (250) 363-6732; Fax: (250) 363-6565 Dear MDD Members, Email: [email protected] Well here it is almost the end of another successful year for • Cliff Stanley (2002-2005) MDD. The executive committee has been doing a great job to Department of Geology, Acadia University, ensure that the Division’s dynamic reputation is being upheld, Wolfville, NS, B4P 2R6; Tel: (902) 585-1344; Fax: with their sponsorship of numerous short courses, field trips (902) 585-1816 and special sessions at the GAC-MAC annual meeting. This Email: [email protected] involves a lot of dedication and hard work by a number of peo- • Ross Sherlock (2003-2006) ple—both on the front lines and behind the scenes. Many ESS/GSC-MRGB/CNGO, Natural Resources thanks and congratulations to those who make it happen! Canada, 626 Tumiit Building, P.O. Box 2319, It is with great pleasure that I am announcing one very impor- Iqaluit, NU; Tel (867) 979-3539; Fax: (867) 979- tant accomplishment of MDD that has recently taken place. 0708 The back issues of the GANGUE (volumes 1 through 82) are Email: [email protected] now available for your viewing pleasure on the MDD website! • Steve McCutcheon (2003-2006) For those interested, the web address is: New Brunswick Department of Natural Re- sources, P.O. Box 50, 495 Riverside Drive, http://mdd.harbour.com/gangue.htm Bathurst, NB; (506) 547-2070; Fax (506) 547- I find it rather interesting to peruse some of the older issues, 7694 just to see how much the newsletter has changed over the years. Email: [email protected] I encourage you to take the time to have a look for yourself. • Gema Olivo (2003-2006) You’ll find some very interesting articles by some very high pro- Geological Sciences, Queens University, King- file economic geologists. If you look hard enough, I’m sure ston, ON; Tel: (613) 533-6998; Fax: (613) 533- you’ll find some interesting tidbits of information (and maybe 6592 even a snicker or two) in some of the many articles. Hats off to Email: [email protected] those that were instrumental in the undertaking of this rather • Steve Rowins (2003-2006) tedious task, particularly Brian Grant who carefully scanned (at Department of Earth and Ocean Sciences, Uni- a very high quality I might add!) all of the hard copies that he versity of British Columbia, Vancouver, BC; Tel: had in his almost complete collection.
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