Challenges of sampling extreme nugget-effect gold-quartz reefs at the New Bendigo Project, Central Victoria, Australia

Johansen, G.F., Raine, M.D., Dominy, S.C., and Bartlett, J. (2003) Challenges of sampling extreme nugget-effect gold-quartz reefs at the New Bendigo Project, Central Victoria, Australia. In: Proceedings of the 5th International Mining Geology Conference. pp. 299-310. From: 5th International Mining Geology Conference, 17-19 Nov 2003, Bendigo, Victoria.

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The Bendigo Goldfield is located in the state of Victoria, Australia, and is one of a number of fields that make up the Central Victorian Goldfield. Since 1993, Bendigo Mining NL has been carrying out an extensive re-evaluation of the goldfield and is currently well advanced in developing an underground mine. The sediment-hosted auriferous quartz reefs are structurally complex and closely associated with anticlinal axes and reverse faulting. The gold within the quartz reefs is characterised by both its coarse nature (100 up to >5000 μm) and its erratic distribution; as a result, the Bendigo Goldfield is classed as an extreme nugget effect system. This characteristic ensures that the Bendigo mineralisation is very challenging to sample and evaluate. In this case, diamond drilling is a good measure of structure and geological continuity, but a poor measure of grade and grade distribution. Drilling, combined with on-reef development, bulk sampling and detailed geological studies are required for resource evaluation. For grade control a balance has to be sought between sample representativness, cost, tum around time and practicality. Extreme nugget effect deposits like Bendigo, require the use of bulk samples in order to be representative. However, the cost and tum around time is significant. As a result, a micro-bulk sampling system has been introduced that attempts to overcome these problems by providing a fast, practical method that can define ore from waste. Bulk sampling and on-vein development arc still necessary for resource and reserve estimation.

Item ID: 14695
Item Type: Conference Item (Research - E1)
Date Deposited: 18 Sep 2017 01:28
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040307 Ore Deposit Petrology @ 100%
SEO Codes: 84 MINERAL RESOURCES (excl. Energy Resources) > 8401 Mineral Exploration > 840105 Precious (Noble) Metal Ore Exploration @ 100%
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