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Location
The Bissa Group Permits cover an area of approximately 1,000 square kilometres in the province of Sanmatenga, approximately 80 kilometres north of the capital city of Ouagadougou in Burkina Faso.
Click on image to enlarge
The Bissa group of exploration permits comprise seven contiguous permits: Zandkom, Bissa, Raka, Tosse, Tema, Gargo and Namtenga. High River owns 100% of the permits except for Zandkom and Bissa (147 sq km) where the Company owns a 90% interest.
Geology and Mineralization
The Bissa group permits are underlain by volcano-sedimentary rocks on the northeast edge of the Boromo greenstone belt, part of the prolific lower Proterozoic Birimian greenstone belts of the West African craton. More particularly, the Bissa Hill deposit is located within the Sabce shear zone, a regional structure which extends for more than 30 kilometres on the property. Gold mineralization is associated with sulphide mineralization and quartz veining hosted in a strongly altered, deformed sedimentary package. The main zone of mineralization forms a northeast trending tabular body steeply dipping to the north.
Exploration Work at Bissa
Substantial work on the project area began in 1993 by a joint venture between Faso Etude et Travaux, a Burkinabe company, and Randgold Resources Ltd. ("Randgold"). At the time, the joint venture encompassed a much larger land position exceeding 2,500 sq km. The project was optioned to Newmont Overseas Exploration Ltd. in 1994-1995 and North Ltd in 1996-2000. Initially, gold mineralization was discovered at Bissa Hill during the 1997-1998 season and was interpreted to be associated with the regional northeast trending Sabce shear zone. During this period, Randgold and its partners conducted extensive exploration work on the Bissa group permits. The work included detailed geophysical surveys, extensive soil sampling, rotary air blast (RAB), reverse circulation (RC) and diamond drilling. In 2001, Delta Gold Ltd. entered into a joint venture agreement with Randgold to explore the properties. Under this agreement, Delta conducted extensive exploration work, including trenching and RC drilling primarily at the Bissa Hill occurrence and the Gougre prospect. This work resulted in the delineation of the near-surface Bissa Hill deposit. In early 2004, Jilbey Gold Exploration Ltd. ("Jilbey") optioned the project and immediately focused its exploration activities on the previously outlined Bissa Hill gold deposit with further work continuing along the strike extension of the deposit (Bissa-Gonglou corridor). In October 2004, Jilbey reported a mineral resource of measured and indicated - 147,250 oz and inferred - 9,970 oz. Positive exploration results prompted High River, which held a 29% equity interest in Jilbey, to merge with that company in September 2005.
In late 2005 and early 2006, High River Gold completed a 31,500 metre drilling programme on the Bissa project which was designed to extend the known gold mineralization southwest along the Bissa-Gonglou corridor. On May 23, 2006 High River Gold announced a substantial increase to the National Instrument 43-101 compliant gold resources to 1.3 million ounces based on this drill programme. Measured and indicated resources increased from 147,250 oz to 662,250 oz while inferred resources grew from 9,970 oz to 679,470 oz as outlined below:
| |
Tonnes |
Grade
(g/t) |
Ounces |
| Measured |
753,000 |
3.39 |
81,980 |
| Indicated |
11,253,000 |
1.60 |
580,270 |
| Inferred |
16,394,000 |
1.29 |
679,470 |
This resource was based on drilling carried out over only a 6 kilometre section of the anomalous 35 kilometre strike length of the Sabce Deformation Corridor. During 2006, High River completed a comprehensive surface exploration programme, which included soil sampling on 100 metre centres over the entire length of the Sabce Deformation Corridor. Based on this work, 12 target areas were identified for drilling.
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In November 2006, High River initiated an exploration programme to test the 12 drill target areas. The objective of this programme is to expand the National Instrument 43-101 resource on the Bissa Group Permits to over 2 million ounces of gold.
During 2007, a drilling programme resulted in the discovery of a new gold zone at Gougre, where 9 holes intersected pervasive alteration and gold mineralization over a 300 metre strike length. At the Bissa South Extension deposit, the structurally complex higher grade IO zone received additional core and RC drilling, enhancing interpretation of the geologic model. Drilling and trenching at the Bissa Southwest deposit were completed to fill-in the shallow part of the deposit. At Gonglou-Boken, RAB drilling returned a number of parallel mineralized zones which will be defined by additional drilling. RC drilling at Guibare and Wemstenga provided targets for follow-up drilling.
In June 2009 High River reported the results of a revised Mineral Resource evaluation completed by SRK Consulting (Canada) Inc. ("SRK"). The revised Mineral Resource estimate was prepared following the National Instrument 43-101 guidelines and incorporated new assay results from drilling and trenching performed by High River during 2007 and 2008. It was prepared to support conceptual mine design work currently being completed by engineering consultants GENIVAR ("GENIVAR") to evaluate the feasibility of an open pit mining and processing operation at Bissa. The effective date of the Mineral Resource Statement was April 23, 2009. The Mineral Resource Statement was contained within a Technical Report prepared by SRK dated June 18, 2009.
Relative to the previous Mineral Resource estimate incorporating Mineral Resource evaluations dated September 28, 2004 and May 23, 2006, Measured Mineral Resources increased by 11%, Indicated Mineral Resources increased by 43%, and Inferred Mineral Resources increased by 18%, as follows:
Bissa Gold Exploration Project Mineral Resource Estimate* (100% basis)
Resource
Category |
Measured and Indicated Resources |
| Tonnage (t) |
Gold Grade (g/t) |
Contained Gold (oz) |
| Measured |
906,000 |
3.13 |
91,000 |
| Indicated |
15,010,000 |
1.73 |
834,000 |
| Total |
15,917,000 |
1.81 |
926,000 |
Resource
Category |
Inferred Resources |
| Tonnage (t) |
Gold Grade (g/t) |
Contained Gold (oz) |
| Total Inferred |
17,730,000 |
1.40 |
799,000 |
* All figures rounded to reflect the relative accuracy of estimates. Reported Resources are within optimized pit shells at a cut-off grade of 0.5 g/t gold
The revised Mineral Resource estimate is constrained within conceptual pit shells and includes only those resource blocks exhibiting "reasonable prospects for economic extraction" from an open pit mine after considering certain additional physical and economic constraints (please see note #3 below, under section titled "Resource Estimate").
The revised Mineral Resource estimate was based on assay results derived from samples taken from 118 trenches (11,935 metres), 181 diamond drill holes (23,068 metres), and 462 reverse circulation drill holes (43,823 metres) completed over the period 2004 to 2008.
After review of the Bissa data, SRK concluded that:
- There is an opportunity to upgrade the resource classification of portions of the Bissa gold mineralization with additional infill drilling targeting the Inferred Mineral Resources near surface at Zone 51W, IO, Bissa SW and Zone 51E.
- There is potential to increase the gold resource at IO with step-out and infill drilling along strike and down plunge, as the controls on the distribution of the higher grade gold mineralization in IO are not well understood.
- Gold mineralization is open along strike to the southwest of Zones 51W and 52.
- Gold mineralization in most of the auriferous zones extends at depth into fresh rock below the current drilling, providing an opportunity to expand the gold Mineral Resources at depth, especially in Zone 52 where the depth of the conceptual pit shells used to report Mineral Resources is limited by data availability.
Notes to the Mineral Resource Estimate:
- The Qualified Persons responsible for the preparation of this NI 43-101 compliant resource estimate are Dr. Jean-Francois Couture, P.Geo., Principal Resource Geologist; Martin Pittuck, C. Eng, Principal Resource Geologist; and James Gilbertson, C.Geol , Senior Exploration Geologist; all with SRK. Dr. Couture, Mr. Pittuck, and Mr. Gilbertson have reviewed the content of this news release. A complete technical report will be filed on SEDAR within 45 days.
- The effective date of the Mineral Resource Statement is April 23, 2009.
- Details of the key assumptions, parameters, and methods used to estimate the above Mineral Resource estimate are as follows:
The Mineral Resources were estimated using a geostatistical block modelling approach constrained by gold mineralization wireframes. Gold grades were estimated using ordinary kriging based on capped composited data and estimation parameters derived by variography.
In order to determine the quantities of material offering reasonable prospects for economic extraction from an open pit, SRK used a pit optimizer to evaluate the profitability of each resource block based on optimization parameters derived, in part, from ongoing engineering studies undertaken by High River and adjusted where appropriate.
| Key assumptions and parameters |
Values |
| Wireframe external cut-off grade |
0.2 g/t |
| Resource block model internal block cut-off grade |
0.5 g/t |
| Pit optimizer gold price |
US $910/oz |
| Pit optimizer metallurgical recovery (CIL) |
90% |
| Pit optimizer mining and processing costs (open-pit, CIL) |
US $20/tonne processed |
| Pit optimizer pit slope |
45 degrees |
| Grade Capping levels (trenches) |
10 g/t |
| Grade Capping levels (drill holes) |
15-25 g/t |
The reader is cautioned that the results from the pit optimization work are used solely for the purpose of reporting Mineral Resources that have "reasonable prospects" for economic extraction by an open pit and do not represent an attempt to evaluate Mineral Reserves for this project.
Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. There is no certainty that all or any of the Mineral Resources will be converted into Mineral Reserves.
Measured Resources are those portions of the block model that have good continuity, good quality local grade estimation, and are defined by tight drill spacing (20 metre drill spacing).
Indicated Resources are those portions of the block model that exhibit good continuity and reasonable quality local grade estimation.
Inferred Resources were all remaining resource blocks.
- SRK is unaware of any environmental, permitting, legal, title, taxation, socio-political, marketing or other issues which would materially affect the Mineral Resource estimates.
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