West Angelas

Western Australia, WA, Australia

Main commodities: Fe
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West Angelas is located some 110 km west of Newman, 110 km south-east of Mt Tom Price and 330 km from the coast in the Hamersley Basin of Western Australia.

West Angelas is one of a number of large Marra Mamba Iron Formation resources and is composed of a group of deposits that are mainly martite - ochreous goethite ores which carry around 0.065% P, 3.5% SiO2, 2.2% Al2O3 and 6.5% LOI.   The lump to fines ratio of the reserve is 33:67.   A production of 7.9 Mt was planned or the first year of operation in 2002, and had increased to 54 Mtpa by 2009.

See the Hamersley Basin Iron Province record for the regional setting and stratigraphy.

The two larger orebodies are found within the Marra Mamba Iron Formation, in association with synclinal structures on the flanks of the west plunging Wanna Munna Anticline, although other minor deposits located around the anticline do not appear to be related to synclines.   Mineralisation is mainly developed in the Mt Newman Member, the uppermost of the Marra Mamba Iron Formation, with minor occurrences in the West Angelas Member at the base of the overlying Wittenoom Dolomite.

The Marra Mamba Iron Formation has been sub-divided into three units, commencing with the basal 135 m thick Nammuldi Member comprising cherty BIF interbedded with thin shales, followed by the medial 35 m thick MacLeod Member made up of BIF, chert and carbonate with numerous shale interbeds.   The uppermost Mount Newman Member hosts most of the mineralisation and is 60 m of interbedded BIF with carbonate and shale.

These are conformably overlain by the West Angelas Member, the basal of three recognised packages that make up the Wittenoom Dolomite.   This member is 40 m thick, composed of shale (often manganiferous), chert and dolomite with minor BIF near its base.   The other succeeding members comprise a 150 m thick package of crystalline dolomite with minor chert, capped by an alternating shale, dolomite and minor chert package.

In March 2000, prior to the commencement of operations in 2002, probable reserves totalled 440 Mt @ 62% Fe, with a further 585 Mt @ 61.5% Fe in the indicated + inferred category.

Reserves and resources at the end of 2011 (Rio Tinto 2012) were:
    Total proved + probable reserves - 297 Mt @ 61.6% Fe, plus
    Total measured + indicated + inferred resources - 218 Mt @ 61.9% Fe (in addition to reserves).

The mine is owned and operated by Robe River Iron Associates, an unincorporated joint venture of Rio Tinto Ltd (53%), Mitsui Iron Ore Development Pty Ltd (33%), Nippon Steel Australia Pty Ltd (10.5%) and Sumitomo Metal Australia Pty Ltd (3.5%).

The most recent source geological information used to prepare this summary was dated: 2002.    
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.

  References & Additional Information
   Selected References:
Harmsworth R A, Kneeshaw M, Morris R C, Robinson C J, Shrivastava P K  1990 - BIF Derived Iron Ores of the Hamersley Province: in Hughes FE (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne   v1 pp 617-642

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 takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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