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Jack Hills |
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Western Australia, WA, Australia |
| Main commodities:
Fe
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Jack Hills iron deposits are located 380 kilometres north-east of the Pacific Ocean port of Geraldton in the Narryer Terrane of the north-western Yilgarn Craton, Western Australia.
For details of the regional setting, see the Narryer Terrane section of the Yilgarn Craton record.
The Jack Hills comprise an 80 km long, ENE-trending, tectonically interleaved, metamorphosed and polydeformed belt composed of a mixture of granite, mafic intrusions and meta-sedimentary rocks, predominantly derived from sedimentary (alluvial fan-delta) siliciclastic protoliths, and minor mafic/ultramafic units and chemical sediments. The dominant lithologies are banded iron formation, chert, ultramafics, mafic schists, granitoids, pelitic schist, quartzite and conglomerate.
The protolith age of the Narryer Gneiss Terrane is variable, generally considered to be in excess of 3.6 Ga, with areas of >3.3 Ma but including rocks as old as 4.4 Ga.
The host jaspilites or banded iron formations (BIF) contain banded hematite-quartzites within a synformal structure. The BIFs typically contain 50% Fe within a lower grade 25% Fe host. Enrichment of the iron has taken place in zones of folding and shearing with mineralisation often in lenses of 62 to 66% Fe.
The H1 and H2 lenses contain most of the Measured Resource and have grades of 64 to 65.5% while the H8 has grades of over 66.5% Fe. Individual lenses are generally a few hundred metres long. Some supergene enrichment mineralisation has been noted and the deposits form topographic highs minimising the stripping ratio. Mineralisation continues to depths of at least 100 m.
Based on exploration during the 1970's, the Jack Hills Project has an estimated DSO hematite potential of 380 Mt @ 62% Fe (non-JORC compliant resource).
Total JORC compliant probable ore reserves at the Jack Hills Project in 2006 were calculated at 8.5 Mt @ 63% Fe, while resources were estimated at 67 Mt @ 62% Fe with significant potential for enlargement to 300 Mt.
Phosphorous is well below 0.05%. Silica levels are generally below 5% and sulphur is negligible. Manganese is usually <0.5%.
Reserves in 2009 were estimated to be 96.6 Mt of direct shipping ore (DSO) and 435 Mt of beneficiation feed ore (BFO).
Total JORC compliant resources in 2013 were 3.89 Gt @ 29.54% Fe, with more than 70% in measured and indicated categories.
Jack Hills Iron Ore project is owned and operated (2013) by Crosslands Resources, a subsidiary of Mitsubishi Development Pty Ltd.
The most recent source geological information used to prepare this decription was dated: 2006.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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