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Granny Smith mine, Australia

20th November 2020

By: Sheila Barradas

Creamer Media Research Coordinator & Senior Deputy Editor

     

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Name:  Granny Smith mine.

Location: Granny Smith is situated within the Yilgarn Craton at 400 m above mean sea level in the Laverton district of the Eastern Goldfields of Western Australia.

Mine Owner/s: GSM Mining Company, a wholly owned subsidiary of Gold Fields.

Brief Description: GSM is mining four zones from the Wallaby orebody – zones 70, 80, 90 and 100 – and developing initial access to Zone 110/120. All ore zones are accessed from a single primary decline. Mining administration and maintenance is located at the Wallaby mine. Ore is processed at the GSM  carbon-in-pulp (CIP) processing plant under campaign milling conditions.

Brief History: The Goanna and Granny Smith deposits were discovered in 1979 by CSR Limited. Placer Pacific acquired CSR’s 60% interest in 1988, with the remaining 40% held by Delta Gold.

Mining started at the Granny Smith pit in 1989 and continued concurrent with the development of the Goanna and Windich pits and nearby satellite pits. In 1992, the Keringal and Sunrise deposits were discovered. Six years later the Wallaby deposit was discovered. The Wallaby openpit was mined from October 2001 until December 2006. Underground mining started at Wallaby in December 2005.

Barrick acquired 100% of Placer Dome shares in 2006.

Gold Fields acquired 100% of the Granny Smith gold mine in 2013, as part of the purchase of the Yilgarn South operations.

Primary Metals/Minerals: Gold.

Secondary Metals/Minerals: None stated.

Geology/Mineralisation: The Granny Smith region is dominated by the Mt Margaret dome in the north-west and the Kirgella dome in the south-east. These domes are flanked to the east and west by northwest-north-striking shear zones, with the central zone between the two domes being dominated by north to north-northeast-striking sigmoidal shear zones.

These distinctly different strikes to the shear zones developed early in the tectonic evolution and resulted in a favourable architecture for late-stage orogenic gold mineralisation at Wallaby and Granny Smith. Orogenic greenstone gold deposits are hosted in several different styles of lodes. The lodes comprise vein stock works localised by a northerly trending shear at the margin of a granodiorite. The Wallaby lodes are flat lying alteration zones hosted within magnetite amphibole altered conglomerate.

Mineralised zones show moderate to long range geological continuity and short range grade continuity.

Reserves: Total proven and probable reserves as at December 30, 2019, were estimated at 12.49-million tonnes grading 5.18 g/t gold.

Resources: Total mineral resources as at December 31, 2019, were estimated at 49.42-million tonnes grading 5.23 g/t gold.

Mining Method: Underground – room and pillar, bulk stopes and longhole open stoping.

Major Infrastructure and Equipment: Gruyere comprises one active underground mine. A 3.5-million-tonne-a-year processing plant, consisting of two crushing circuits, semiautogenous grinding and ball mills, leach and CIP circuits and a tailings retreatment circuit. However, the processing plant is mine constrained and currently operates at 1.5-million tonnes a year on a campaign milling basis.

Prospects: Extensional and brownfield exploration continues at the mine, which will sustain an extended life-of-mine well beyond current proven and probable reserves reporting. It is estimated that the current mineral reserves are sufficient for a 12-year mine life.

Contact Details:
Gold Fields (Australia)
Tel +61 8 9211 9203
Email info@goldfields.com
Website https://www.goldfields.com

 

Edited by Creamer Media Reporter

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