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Nickel-Copper exploration target at Tamarack, Minnesota, USA

Assays from twenty-two mineralised drill holes have identified a +750 metres long body of nickel-copper sulphide mineralisation open up-plunge, down-plunge and to depth. Preliminary metallurgical test work shows excellent recoveries for both nickel and copper.

Exploration target	Tonnage Range (millions)	_{Grade Range}
Tamarack Nickel	9-11	1.0 - 1.1% Ni and 0.6 - 0.7% Cu

Location and Title

The Tamarack project, 75 kilometres west of Duluth, is 100 per cent owned by Rio Tinto. There is excellent established infrastructure including a paved highway adjacent to the deposit and power and rail lines within three kilometres.

Location map

Summary of Exploration Results

The Tamarack deposit was located by geophysics and reconnaissance drilling within the northern portion of a plus 15 kilometre long Proterozoic mafic-ultramafic intrusion concealed beneath 20-30 metres of glacial cover. Most of the larger intrusive system remains untested. Tamarack mineralisation comprises disseminated, semi-massive and massive sulphides within a late gabbroic phase. Massive sulphide lenses occur in country rock metasediments peripheral to the intrusion.

3D model of Tamarack long section

Table of significant intercepts

Hole	From (m)	To (m)	Interval (m)	%Ni	%Cu	%Co	ppm Pt	ppm Pd	ppm Au
08L042	325.6	464.0	138.4	1.61	1.06	0.04	0.32	0.22	0.18
08TK0048	332.5	476.5	144.0	1.93	1.16	0.05	0.40	0.26	0.22
08TK0049	396.0	408.0	12.0	6.03	3.30	0.11	0.67	0.59	0.33
08TK0058	473.0	558.5	85.5	2.09	0.96	0.06	0.58	0.35	0.24
08TK0067	421.5	506.5	85.0	2.40	1.18	0.06	0.55	0.32	0.23
08TK0074	326.5	398.5	72.0	1.48	0.88	0.04	0.15	0.10	0.12
08TK0075	449.0	504.0	55.0	3.38	1.65	0.09	0.58	0.38	0.22
08TK0077	396.4	409.9	13.6	5.82	2.68	0.13	0.51	0.44	0.22
08TK0079	458.7	525.5	66.8	2.24	1.13	0.06	0.39	0.27	0.18
08TK0081	421.1	431.6	10.5	4.98	3.04	0.09	0.96	0.52	0.28
08TK0081	455.5	524.0	68.5	1.79	0.94	0.05	0.60	0.35	0.27
08TK0083	497.5	507.8	10.3	7.01	2.89	0.14	1.51	0.70	0.30
08TK0086	501.5	560.0	58.5	2.04	0.95	0.06	0.51	0.32	0.27
08TK0089	316.8	483.0	166.2	2.33	1.24	0.06	0.34	0.23	0.18
08TK0090	350.9	461.5	110.6	0.89	0.64	0.02	0.30	0.17	0.17

* Reported intervals are continuous mineralized drill intercepts where composite Ni% multiplied by composite meters is greater than 50. Composite boundaries are determined using a 0.4% Ni cut-off. Intervals contain a maximum of 10% internal dilution of <0.4% Ni material.

The exploration target being reported under clause 18 of the JORC Code is based on assessments of prospects within Rio Tinto's 100 per cent owned tenure which are supported by drilling, geophysics, metallurgical test-work and modelling undertaken over the last year. However, the potential quantity and grade is conceptual in nature, there has been insufficient exploration to define a Mineral Resource and it is uncertain if further exploration will result in definition of a Mineral Resource.

CP Statement

The information in this presentation that relates to Exploration Results is based on information compiled by Steven Coombes who is a Member of the Association of Professional Engineers and Geoscientists of British Columbia, a JORC Recognised Overseas Professional Organisation (ROPO). Steven Coombes is a full time consultant for Rio Tinto and has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person as defined in the 2004 Edition of the 'Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves'. Steven Coombes consents to the matters based on his information in the form and context in which it appears.

Nickel-Copper exploration target at Tamarack, Minnesota, USA [PDF: 92 KB]