Mount Tom Price

Western Australia, WA, Australia

Main commodities: Fe
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The Mount Tom Price mine, which commenced production in 1965 is located some 210 km WNW of Newman and 260 km SSW of its export port of Dampier. It is owned and operated by Rio Tinto Iron Ore. The orebody at Mount Tom Price originally contained the second largest known accumulation of high grade hematite in the Hamersley province and occurs near the keel of the large Turner Syncline, close to its eastern extremity (#Location: 22° 46' 11"S, 117° 46' 27"E).

The deposit is some 7.5 km long and up to 1.6 km wide, but averages 0.6 km, occupying two local synclines and part of the intervening anticline. These early folds have been subjected to later cross folding producing an en echelon pattern, while two south dipping normal faults parallel and in part limit the ore. The base of the northern syncline is higher than that of the southern giving an overall southerly dip and apparent thickness of 150 m, extending to a depth of 250 m below surface.

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

The Mount Tom Price orebody is composed mainly of micoplaty hematite within the Brockman Iron Formation, with the majority of the ore associated with the Dales Gorge and underlying Colonial Chert Members. The deepest drilling at the mine is generally to the top of the Marra Mamba Iron Formation which is overlain by the 150 m thick Paraburdoo Member (the carbonate unit of the Wittenoom Formation), that passes up into the shaly 157 m thick Bee Gorge Member, followed by the 30 to 40 m thick cherty Mount Sylvia Formation. The overlying 50 m thick Mount McRae Shale is composed of black pyritic shale, capped by the uppermost unit of the Wittenoom Formation, a 12 m thick chert band, the Colonial Chert Member.

The Colonial Chert is followed by the 150 m thick basal Dales Gorge Member of the Brockman Iron Formation, comprising 17 alternations of BIF and shale. These have been grouped into 3 sub-units on the basis of shale content. The lowest, DG1, and uppermost DG3 have 6% and 7% shale respectively, while the intervening DG2 has 31%. The Dales Gorge is overlain by the 50 m thick Whaleback Shale Member composed of green to black shale and chert, which is in turn followed by a 360 m thick BIF unit with only minor shale, the Joffre Member.

Some 90% of the ore at Mount Tom Price is within the Dales Gorge Member, with local enrichment in the Joffre Member where it is in fault contact with mineralised Dales Gorge. The remainder of the ore is in the Colonial Chert and Whaleback Shale Members. Primary Dales Gorge Member BIFs away from any enrichment are dominated by chert and magnetite, accompanied by variable, but lesser hematite, carbonate and Fe-silicates. The high grade mineable reserves at Mount Tom Price are present as hematite ore which preserves the meso- and micro-banding of the original BIF, is characteristically porous (averaging 30% porosity), has a high lump yield and low contaminants. In places the porous ore alternates with dense bright metallic lustre hematite with only around 4% porosity to produce a defined banding. It is essentially composed of randomly oriented fine grained platy hematite and martite with individual plates being 0.001 to 0.25 mm across. Fusing of these micro-plates, gives the lump ore its character. Ultra-fine earthy hematite filling the voids is generally less than 5%. Shale macro-bands within the orebody have been partially replaced by iron oxides and at times may exceed 50% Fe.

The orebody was capped by a variable layer of low grade hydrated material, predominantly goethite, averaging 18 m in thickness, but down to 50 m in synclinal troughs. It has an irregular and patchy distribution controlled by fractures and joints, etc.. Minor deposits of 'canga' - 1 to 20 cm fragments of hematite and/or BIF cemented by goethite - occur as scree deposits and hillside wash in streams.

The initial reserve totalled around 900 Mt @ 64% Fe with a high lump to fines ratio, and low impurities (Harmsworth et al., 1990);
Mining to the end of 1972 had produced 134 Mt @ 61.8% Fe (Gilhome, 1975);
Remaining reserves (and resources) in 1974 were 610 Mt @ 62.6% Fe (Gilhome, 1975);
The impurity content of the high grade ore reserve in 1990 was 0.053% P, 3.5% SiO2 and 1.9% Al2O3 (Harmsworth et al., 1990).
Remaining reserves and resources in 2007 (Rio Tinto, 2008 Annual Report; reserves are additional to resources) were:
      Proven + probable Brockman reserves - 125 Mt @ 64.4% Fe;
      Proven + probable Marra Mamba reserves - 33 Mt @ 61.2% Fe;
      Measured + indicated + inferred high grade Brockman resources - 100 Mt @ 63.9% Fe;
      Measured + indicated + inferred low grade Brockman resources - 60 Mt @ 55.9% Fe;
      Measured + indicated + inferred Marra Mamba resources - 15 Mt @ 61.8% Fe;
Remaining reserves and resources in 2010 (Rio Tinto 2010 Annual Report; reserves are additional to resources) were:
      Proven + probable Brockman reserves - 83 Mt @ 63.6% Fe;
      Proven + probable Marra Mamba reserves - 20 Mt @ 61.2% Fe;
  High grade:
      Measured resources - 35 Mt @ 63.3% Fe;
      Indicated resources - 67 Mt @ 63.8% Fe
      Inferred resources - 9 Mt @ 64.4% Fe.
  Low grade:
      Measured resources - 26 Mt @ 56.9% Fe;
      Indicated resources - 25 Mt @ 55.6% Fe
      Inferred resources - 3 Mt @ 55.0% Fe.
  Marra Mamba:
      Measured resources - 14 Mt @ 61.9% Fe;
      Indicated resources - 3 Mt @ 61.8% Fe.

The most recent source geological information used to prepare this summary was dated: 2010.    
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.

Mount Tom Price

  References & Additional Information
   Selected References:
Barley M E, Pickard A L, Hagemann S G, Folkert S L  1999 - Hydrothermal Origin for the 2 Billion Year Old Mount Tom Price Giant Iron Ore Deposit, Hamersley Province, Western Australia: in    Mineralium Deposita   v34 pp 784-789
Bitencourt R, Mackenzie P, Gordon J, Morey B  2002 - High Grade Optimisation and Improved Grade Control Practices in Mount Tom Price: in   Proceedings, Iron Ore 2002 Conference, 9-11 September 2002, Perth, Western Australia, The AusIMM, Melbourne    pp 261-277
Dalstra H and Guedes S  2004 - Giant Hydrothermal Hematite Deposits with Mg-Fe Metasomatism: A Comparison of the Carajás, Hamersley, and other Iron Ores: in    Econ. Geol.   v99 pp 1793-1800
Ewers W E, Morris R C  1981 - Studies of the Dales Gorge Member of the Brockman Iron Formation, Western Australia: in    Econ. Geol.   v76 pp1929-1953
Gilhome W R  1975 - Mount Tom Price Iron Orebody, Hamersley Iron Province: in Knight CL (Ed.), 1975 Economic Geology of Australia & Papua New Guinea, Monograph 5 The AusIMM, Melbourne   v1 - Metals pp 892-898
Gutzmer, J., Chisonga, B.C., Beukes, N.J. and Mukhopadhyay, J., C.A.,  2008 - The geochemistry of banded iron formation-hosted high-grade hematite-martite iron ores: in Hagemann S, Rosiere C, Gutzmer J and Beukes N J, (eds.), 2008 Banded Iron Formation-Related High-Grade Iron Ore, Reviews in Economic Geology   v.15 pp. 157-183
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
McLellan J G, Olivera N H S, Schaubs P M,  2004 - Fluid flow in extensional environments; numerical modelling with an application to Hamersley iron ores: in    J. of Structural Geology   v26 pp 1257-1171
Morris R C  1980 - A textural and mineralogical study of the relationship of iron ore to banded iron-formation in the Hamersley Iron Province of Western Australia : in    Econ. Geol.   v75 pp 184-209
Taylor D, Dalstra H J, Harding A E, Broadbent G C, Barley M E,  2001 - Genesis of High-Grade Hematite Orebodies of the Hamersley Province, Western Australia: in    Econ. Geol.   v96 pp 837-873
Thorne W S, Hagemann S G and Barley M E,  2006 - Hydrothermal alteration zonation and fluid chemistry of the Southern Ridge and North deposits at Mt Tom Price: in    Trans. IMM (incorp. AusIMM Proc.), Section B, Appl. Earth Sc.   v115 pp 152-160
Thorne W, Hagemann S, Vennemann T and Oliver N,   2009 - Oxygen Isotope Compositions of Iron Oxides from High-Grade BIF-Hosted Iron Ore Deposits of the Central Hamersley Province, Western Australia: Constraints on the Evolution of Hydrothermal Fluids: in    Econ. Geol.   v104 pp 1019-1035
Thorne W, Hagemann S, Webb, A and Clout, J,  2008 - Banded iron formation-related iron ore deposits of the Hamersley Province, Western Australia: in Hagemann S, Rosiere C, Gutzmer J and Beukes N J, (eds.), 2008 Banded Iron Formation-Related High-Grade Iron Ore Reviews in Economic Geology   v.15 pp. 197–221
Thorne WS, Hagemann SG, and Barley M,  2004 - Petrographic and geochemical evidence for hydrothermal evolution of the North Deposit, Mt Tom Price, Western Australia: in    Mineralium Deposita   v39 pp 766 - 783
Webb, A.D., Dickens, G.R. and Oliver, N.H.S.,  2003 - From banded iron-formation to iron ore: geochemical and mineralogical constraints from across the Hamersley Province, Western Australia: in    Chemical Geology   v.197 pp. 215-251

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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