Riverstone Increases Gold Resources at Karma by 70 Percent
VANCOUVER, BRITISH COLUMBIA -- (Marketwire) -- 02/28/11 -- Riverstone Resources Inc. (TSX VENTURE: RVS)(FRANKFURT: 3RV) has received an independent resource estimate, which shows a substantial increase in the gold mineral resources at its flagship Karma project in Burkina Faso, West Africa. The NI 43-101 compliant resource estimate has increased the contained ounces of gold by 70% from the Company's initial estimate of May 2009. The total discovery cost of the increase in resources was less than $6 per ounce of gold.
HIGHLIGHTS
-- Indicated gold resources are 810,600 ounces of gold in 22,845,000 tonnes
at a grade of 1.10 g/t.
-- In addition, the inferred gold resources are 1,119,100 ounces of gold in
44,110,000 tonnes at a grade of 0.79 g/t.
-- The gold resources are at shallow depths and over 90% of the gold
resource is within 150 metres from surface.
-- Mineralization remains open at depth and along strike.
-- The resource estimate only includes drill hole results received up to
October 2010 and results of an additional 13,000 metres of drilling,
completed since that time, are not included. Most of the newest drill
results include significant mineralized intervals. Data from this and
on-going drilling will be incorporated into the next resource estimate.
-- The prospective Nami deposit drill results have not been included in
this resource estimate.
-- This is an interim estimate and will be updated again later in the year.
Michael D. McInnis, President and CEO of Riverstone Resources commented, 'We are extremely pleased with the material increase in the gold resource at Karma. There is ample room to increase the gold resource and to establish Karma as one of the premier gold projects in West Africa. We are presently drilling with two rigs and plan to add up to three more rigs as they become available.'
The Karma project consists of four separate deposits, which are located close to each other. A summary of the resource estimates for each deposit is presented in the table below:
TABLE 1 SUMMARY OF KARMA RESOURCE(i)
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Category Type Tonnes Grade (g/t) Gold - oz
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RAMBO MAIN
Indicated Oxide 290,000 3.64 33,900
Sulphide 429,000 3.37 46,400
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Total 719,000 3.48 80,300
Inferred Oxide 145,000 1.12 5,200
Sulphide 325,000 1.54 16,100
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Total 470,000 1.41 21,300
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KAO
Indicated Oxide 9,070,000 0.77 225,000
Sulphide 2,918,000 0.90 84,100
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Total 11,988,000 0.80 309,100
Inferred Oxide 5,601,000 0.52 93,300
Sulphide 10,165,000 0.94 305,900
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Total 15,766,000 0.79 399,200
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GG II
Indicated Oxide 5,746,000 1.20 221,400
Sulphide 4,392,000 1.41 199,800
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Total 10,138,000 1.29 421,200
Inferred Oxide 2,577,000 0.69 57,300
Sulphide 5,487,000 1.16 204,000
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Total 8,064,000 1.01 261,300
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GG I
Inferred Oxide 7,896,000 0.59 150,400
Sulphide 11,914,000 0.75 286,900
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Total 19,810,000 0.69 437,300
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TOTAL RESOURCES
Indicated 22,845,000 1.10 810,600
Inferred 44,110,000 0.79 1,119,100
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(i) Mineral resources are not mineral reserves and do not have demonstrated
economic viability. Resources classified as 'Oxide' contain both oxide
and oxide transitional resources. Cut-off grades used were 0.25 g/t for
oxide and 0.40 g/t for sulphide except for Rambo where the cut-offs
were 0.50 g/t and 1.00 g/t respectively. The reported resources were
calculated using un-capped gold values; using capped values the global
resource is reduced by approximately 3.8% or 74,300 ounces. These
numbers are rounded to the nearest thousand tonnes and hundred ounces.
The mineral resource was estimated by independent consultants John A. Zbeetnoff, P.Geo., and Giles R. Peatfield, Ph.D., P.Eng. The geological interpretations for the four deposits modelled in the 2010 Karma Resource estimate were completed using a base case of a nominal 6 metre minimum drilled length and a nominal assay cut-off grade of 0.25 g/t gold. The interpretations outlined multiple mineralized bodies in each deposit. Each mineralized body was created as a wireframe and these were ultimately used as hard boundaries to limit grade interpolation.
Grade modelling was completed using 2.0 metre composites and an Inverse Distance Cubed ('ID3') formula. Composite grades were determined with length weighted capped and un-capped assay values. Capping levels were deposit specific and ranged from 12 to 22 g/t gold. Bulk density values used for the tonnage factor were 2.00 for oxide and 2.75 for sulphide resources.
The search ellipse orientation for each mineralized body was determined by manually contouring the pierce point values represented by the mathematical product of the grade multiplied by the true thickness for each hole that pierced the wire frame. These contours were generated on either vertical or inclined longitudinal sections.
All reported resources fell within the limits of the mineralized wire frames. All blocks or partial blocks within a wire frame needed to have at least three holes within 50 metres to be classified as Indicated Resource. Inferred Resources were determined from the remaining blocks, or partial blocks that lie within the wire frames and within 50 metres of a drill hole.
Each deposit was modelled in a unique partial block model project in Gemcom Software.
Assay data included in the estimates have been independently verified from original assay reports.
Riverstone Resources Inc. is active in gold exploration in Burkina Faso, West Africa, where the Company holds an extensive portfolio of six high quality exploration projects covering 2,300 square kilometres. The Goulagou permit is subject to an option to purchase agreement with Golden Star Resources. For further information about the Company and its activities, please refer to the Company's website at www.riverstoneresources.com and under the Company's profile at www.sedar.com.
ON BEHALF OF THE BOARD
Michael D. McInnis, P. Eng., President & CEO
Giles. R. Peatfield, Ph.D., P.Eng. is a Qualified Person for RVS and has reviewed and approved the contents of this release.
Certain statements made and information contained in this news release and elsewhere constitutes 'forward-looking information' within the meaning of the Ontario Securities Act. Forward-looking statements are subject to a variety of risks and uncertainties which could cause actual events or results to differ from those reflected in the forward-looking statements, including, without limitation, risks and uncertainties relating to the interpretation of drill results and the estimation of mineral resources, the geology, grade and continuity of mineral deposits, the possibility that future exploration, development results will not be consistent with the Company's expectations, accidents, equipment breakdowns, title matters and surface access, labour disputes, the potential for delays in exploration activities, the potential for unexpected costs and expenses, commodity price fluctuations, currency fluctuations, failure to obtain adequate financing on a timely basis and other risks and uncertainties, including those described under Risk Factors in each management discussion and analysis. In addition, forward-looking information is based on various assumptions including, without limitation, the expectations and beliefs of management, the assumed long term price of gold, that the Company will receive required permits and access to surface rights, that the Company can access financing, appropriate equipment and sufficient labour and that the political environment within Burkina Faso will continue to support the development of environmentally safe mining projects. Should one or more of these risks and uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those described in forward-looking statements. Accordingly, readers are advised not to place undue reliance on forward-looking statements.
Contacts:
Riverstone Resources Inc. - Vancouver Office
Michael D. McInnis
President
604-801-5020
Riverstone Resources Inc.
Raju Wani
Investor Relations
403-240-0555
Riverstone Resources Inc.
Ron Cooper
Investor Relations
604-986-0112
info@riverstoneresources.com
www.riverstoneresources.com