Orezone Gold Corporation

Orezone Gold Corporation

August 27, 2012 17:00 ET

Orezone's Bombore Gold Project Reaches World Class Size

Measured and Indicated Mineral Resources up 160% and grade up 27%

OTTAWA, ONTARIO--(Marketwire - Aug. 27, 2012) - Orezone Gold Corporation (TSX:ORE) is pleased to announce that gold mineral resources at its Bomboré Gold Deposit, located in Burkina Faso, West Africa, have substantially increased to:

125 million tonnes of measured and indicated mineral resources at 1.03 g/t for 4.13 million oz,

and 32.1 million tonnes of inferred mineral resources at a grade of 1.00 g/t for 1.03 million oz.

Bomboré is now world class1 and is the largest undeveloped gold deposit in Burkina Faso and possibly in all of West Africa.


  • The mineral resource update includes an additional 214,146 m of drilling for a total of 338,033 m, including 222,184 m of RC drilling (3,510 holes) and 115,849 m of core drilling (764 holes).
  • All resources are contained within optimized pit shells with a maximum depth of 200 m, using current Burkina Faso operating cost and Bomboré recovery parameters and $1400/oz gold;
  • Measured and indicated mineral resources have increased by 2.54 Moz to 4.13 Moz (+160%) with grades increasing by 27% to 1.03 g/t;
  • The measured mineral resource is 1.87 Moz, with none in the previous model;
  • Oxidized measured and indicated mineral resources have increased by 0.71 Moz to 1.76 Moz (+70%) with grades increasing by 32% to 0.94 g/t;
  • Upside potential remains to further upgrade and expand the oxidized resources;
  • The gold mineralization remains open at depth in several major areas with significant potential to further increase the mineral resources amenable to open pit extraction in the fresh rock; and
  • The discovery cost of the Bomboré gold resource to date is approximately $10/oz.

1 Singer, D.A., 1995, World-class base and precious metal deposits-a quantitative analysis: Economic Geology, v. 90, no.1, p. 88-104

The extensive 2011/12 drill program was successful in demonstrating continuity within previously modeled deposits, expanding the mineralized zones and improving the grade of both the near surface oxide resource and underlying fresh rock resource. An additional 35,000 m of definition drilling was completed during Q2 with results planned to be released in September. This recent drilling will further upgrade and expand the Bomboré gold resources. Given the significant potential to further expand the project's mineral resources, the Company's board of directors has approved up to $10 M of additional infill and expansion drilling that will commence in September and run until June 2013.

"Bomboré is the largest undeveloped gold deposit in Burkina Faso and it remains open at depth and along strike" said Ron Little President and CEO. "The average depth of drilling is only 120 m and 43% of the resources are oxidized. The Company will continue to drill and further expand resources while it completes a Definitive Feasibility Study during the first half of 2013."

This material change to the total mineral resource supports the Company's approach to develop the project as a carbon in leach ("CIL") operation in two phases. The ongoing feasibility study contemplates first building an oxide-only plant with the benefits of lower capital costs, lower operating costs and higher recoveries for this initial phase. A second phase expansion to process the harder sulphide resources could then be financed from project cash flows. Detailed metallurgical studies will be released during Q3 and Q4. A new resource update is planned for Q1 2013.

The mineral resource statement (Table 1) was prepared by SRK Consulting (Canada) Inc. ("SRK") from Toronto. The mineral resources are constrained within 6.2 km² of conceptual open pit shells prepared by G Mining Services Inc. (GMS) from Montreal using parameters established by GMS in June 2012 and taking into account the findings of the ongoing metallurgical study (Table 2). The pit shells are based on a US$1,400 gold price, relevant cost estimates for mining, processing and G&A of comparable Burkina Faso gold mines, and detailed metallurgical results to estimate recoveries for a CIL plant scenario. The resources span over 11 km long and up to 1 km wide with an estimated stripping ratio of 2.7:1. The majority of the total resource occurs within the top 120 m, where approximately 95% of the drilling was completed to date, but pit shells can reach a depth of 200 m. Resources remain open at depth and for the most part along strike.

"The pit shell optimization parameters approximate current operating costs in Burkina Faso and represent significant increases in the mining, G&A and processing costs as compared to those parameters used in the 2010 resource estimate and 2011 PEA. Even with such increases, we were still able to reach our target of a +5 Moz deposit at a grade of 1.0 g/t," said Pascal Marquis, Senior V.P. Exploration for Orezone. "Most importantly the deposit is scalable and leveraged to the gold price. Any increase in the gold price or drop in costs yields significantly higher contained ounces."

Table 1 - 2012 Mineral Resource Statement* for the Bomboré Deposit, Burkina Faso, West Africa, SRK Consulting (Canada) Inc., August 20, 2012, CIL Processing Scenario

Category Cut-off Measured Mineral
Indicated Mineral
Inferred Mineral
Gold Tonnage Grade Contained Gold Tonnage Grade Contained
Tonnage Grade Contained
g/t Mt g/t koz Mt g/t koz Mt g/t koz
Laterite/Oxide 0.45 4.89 0.93 146 6.32 0.94 190 2.85 0.85 78
Transitional 0.45 3.65 0.90 105 3.55 0.96 110 2.07 0.82 55
Fresh 0.50 10.37 1.00 333 18.25 1.06 621 9.73 0.97 303
Sub-total 18.91 0.96 585 28.12 1.02 922 14.65 0.93 436
Laterite/Oxide 0.45 0.17 1.32 7 0.40 1.19 15 0.16 0.77 4
Transitional 0.45 0.14 1.68 8 0.18 1.16 7 0.16 0.64 3
Fresh 0.50 1.50 1.56 75 0.64 1.50 31 0.29 0.97 9
Sub-total 1.81 1.54 90 1.22 1.35 53 0.61 0.83 16
Laterite/Oxide 0.45 11.24 0.92 333 15.10 0.91 441 3.46 0.70 78
Transitional 0.45 7.39 0.93 222 5.31 1.00 171 1.57 0.74 37
Fresh 0.50 19.29 1.03 638 16.60 1.27 676 11.85 1.23 467
Sub-total 37.92 0.98 1,193 37.02 1.08 1,288 16.87 1.07 581
Laterite/Oxide 0.45 16.29 0.93 487 21.82 0.92 647 6.47 0.77 160
Transitional 0.45 11.18 0.93 335 9.04 0.99 287 3.80 0.78 95
Sub-total 0.45 27.47 0.94 822 30.87 0.94 934 10.27 0.94 255
Fresh 0.50 31.17 1.04 1,046 35.49 1.16 1,328 21.86 1.11 779
Total 58.64 0.99 1,868 66.36 1.06 2,262 32.13 1.00 1,034
Total M+I 125.00 1.03 4,131
* Mineral resources are not mineral reserves and do not have a demonstrated economic viability. All figures have been rounded to reflect the relative accuracy of the estimates. The cut-off grades are based on a gold price of US$1,400 per ounce and metallurgical recovery of 94 percent for laterite and oxide, 92 percent for transitional material and 82 percent for fresh material. Reported within conceptual open pit shells optimized considering a carbon in leach process option.

Table 2 - 2012 Optimization Parameters used by GMS vs. 2010 Optimization Parameters used by SRK

Category 2012 2010 Category 2012 2010
Gold Price $1,400 $1,025
NSR $70 $41
Lower Cut-off g/t g/t Mining Costs $ $
Oxide 0.45 0.30 Oxide 1.90 1.10
Transition 0.45 0.35 Transition 2.35 1.35
Fresh 0.50 0.50 Fresh 2.44 1.65
Process Recovery % % Processing Costs $ $
Oxide 94 93 Oxide 7.21 6.67
Transition 92 92 Transition 9.76 8.52
Fresh 82 78 Fresh 12.66 10.36
Overall Pit Slopes Degrees Degrees G&A $ $
Oxide 35 37 Oxide 3.84 1.55
Transition 40 42 Transition 3.84 1.67
Fresh 45 50 Fresh 3.84 1.85

Table 3 - 2010 Mineral Resource Statement* for the Bomboré deposit, Burkina Faso, West Africa, SRK Consulting (Canada) Inc., October 15, 2010, CIL Processing Scenario

Indicated Mineral Resource Inferred Mineral Resource
Grade (g/t) Gold
0.30 Oxide 34.0 0.67 0.73 25.0 0.59 0.48
0.35 Transition 11.2 0.84 0.30 5.4 0.88 0.15
0.50 Fresh 15.7 1.10 0.55 30.3 1.28 1.24
TOTAL 60.9 0.81 1.59 60.6 0.96 1.87
* Mineral Resources are not mineral reserves and do not have demonstrated economic viability. All figures have been rounded to reflect the relative accuracy of the estimates. The cut-off grades are based on a gold price of US$1,025 per ounce with CIL processing recoveries of 93% for oxide, 92% for transitional and 78% for fresh material. Indicated and Inferred Mineral Resources are all reported within conceptual optimized open pit shells. Unlike 2008, those resource blocks that occur outside the pits shells are not included in this resource estimate. Mt= million metric tonnes. Moz= million troy ounces; g/t= grams gold per tonne.

Several factors account for the difference between the 2012 and 2010 mineral resource estimates as follows:

  1. Significant increase in drilling data, which resulted in greater confidence in the geological and grade continuity, with improved geological and resource domain modeling;
  2. Revised/enhanced geostatistical inputs including: reduced block size, revised variography, capping, and estimation parameters; and
  3. A higher gold price of US$1,400 was used in this estimate versus US$1,025 in 2010, offsetting the higher cost assumptions and shallower slopes.

Table 4 - 2012 Mineral Resource Sensitivity to Gold Price, CIL Processing Scenario

Measured and Indicated Inferred
1100 78.5 2.65 1.05 20.2 0.66 1.01
1200 97.3 3.05 0.98 26.0 0.79 0.95
1300 112.0 3.49 0.91 41.5 1.17 0.88
1400 142.0 3.88 0.85 56.5 1.50 0.82
1500 167.9 4.31 0.80 74.6 1.86 0.78
1600 193.6 4.70 0.75 99.3 2.36 0.74
1700 218.7 5.05 0.72 129.9 2.95 0.71
Resources are from Whittle runs including 5% dilution and 5% mining losses.

Drilling on the Bomboré property, geological modelling and the mineral resource estimates were supervised by Pascal Marquis, Ph.D., P. Geo., Senior Vice President and Qualified Person for Orezone, as defined by National Instrument 43-101, and who has reviewed and approved the technical information in this release. The mineral resource estimate was prepared by Dorota El-Rassi, P.Eng. and Glen Cole, P.Geo. of SRK; they are Independent Qualified Persons as defined by National Instrument 43-101. The optimization parameters and the Whittle pit optimization were established by Louis-Pierre Gignac, P.Eng., CFA of GMS; he is an independent Qualified Person as defined by National Instrument 43-101. Orezone holds a 100% operating interest in the project while the Government of Burkina Faso will receive a 5% net smelter royalty and a 10% non-participating (carried) interest should the project go into production.

Mineral Resource Estimate Parameters and Methodology

  • Mineral resources were estimated using a conventional geostatistical block modelling approach constrained by mineralization wireframes.
  • Gemcom GEMS™ software was used to construct the geological solids, prepare assay data for geostatistical analysis, construct the block model, estimate metal grades, and to tabulate mineral resources. GEMS™, Leapfrog and GoCad software packages were used to create the three-dimensional geological model in close association with Andre Labonté, an independent geologist contracted by Orezone. The Geostatistical Software Library™ (GSLib) family of software and GEMS™ were used for geostatistical analysis and variography. Whittle 4D was used for the pit optimization.
  • The Bomboré gold project database used for this mineral resource estimate contains drill holes up to March 2012 and assay results up to June 2012.
  • The mineral resource update includes an additional 214,146 m of drilling for a total of 338,033 m, including 115,849 m of core drilling.
  • The drilling data includes survey information readings usually taken at 25 m increments starting at 6 m below the collar for a total of 17,716 readings.
  • The drilling data includes 60,799 specific gravity measurements on core samples usually taken at 2 m intervals.
  • The gold assay data comprises 311,363 gold assays, including 286,682 samples assayed using a leaching procedure and 73,774 assay results for the leach residues of mineralized samples.
  • The Bomboré gold project can be divided into three geographic areas comprising eight main gold deposits; i.e. the KT, Maga, CFU and P8P9 deposits in the North area, the P11, Siga West and Siga East deposits in the South area and the P16 and P17 deposits in the Southeast area.
  • Four main lithological domains were refined by the statistical evaluation of the field X-ray fluorescence data obtained on all the Orezone core samples and all of the 2011-12 RC samples.
  • The low grade domain was subdivided in three sub-domains based on the 0.1 and 0.3 g/t cut-offs.
  • Leapfrog shells based on a threshold value of 1.0 g/t gold were found to exhibit good spatial continuity and were found to best differentiate the high grade mineralization from the surrounding low grade mineralization. These shells were used as a guide for modelling the boundaries of the higher grade gold mineralization within the low grade envelopes on vertical sections.
  • The resulting low-grade and high grade wireframes were used as resource domains to constrain grade estimation.
  • Orezone has provided SRK with digital topography and three weathering surfaces (Laterite, Oxide and Transition) delineated by geological logging that was validated using the specific gravity data and the XRF litho-geochemical data.
  • For mineral resource evaluation, in situ gold grades are estimated from the available assaying data. The total "in situ" gold content is determined by adding the partial leach gold value (LeachWell or BLEG) with the gold content in the leach residue either assayed or estimated. For the South area, no estimation of the missing leach residue assay was made as those only represented about 10% of the samples, allowing for a representative in situ grade modeling. For the North and Southeast area, SRK has estimated the missing leach assays using a linear regression of the conditional mean of the (fire assay / LeachWell) ratio against the LeachWell results.
  • Geostatistical analysis, capping, variography and estimation were conducted on the "in situ" gold data.
  • Gold assay data within all domains were composited to a length of 1.5 m.
  • For each domain, a capping value was determined by analyzing histograms and cumulative frequency plots of "in situ" gold composites in each domain separately. Capping values were adjusted iteratively by referring to summary statistics to ensure the robustness of the statistics for the chosen capping values, which are comprised between 1 and 35 g/t depending on the grade domain.
  • The block model was populated with an "in situ" gold value using ordinary kriging from up to three estimation passes, with estimation parameters derived from variography. "Soft" and "hard" domain boundaries were considered for estimation and each resource domain was estimated separately.
  • The block model was also populated with a specific gravity value using an inverse distance algorithm informed from a large database of specific gravity measurements on core samples.
  • Variography was performed using the GSLib software using uncapped 1.5 m "in situ" gold composites. Both directional and isotropic variograms were calculated.
  • As a validation check of the ordinary kriging estimates, gold was also estimated using an inverse distance estimator. Results from the two estimators were compared visually and both estimators deliver very similar results. SRK prefers to report gold grades estimated by ordinary kriging because the spatial continuity and nugget effect can be modeled using variograms, and also because ordinary kriging delivers an estimate of the quality of the estimates in the form of the kriging variance.
  • Block classification involved a two-step process. The first step is an automated classification that considered four main criteria: the number of composites used to code a block, the estimation pass, the average distance to informing composites, and the kriging variance. Blocks coded during the first search pass were assigned an Indicated classification. All blocks interpolated during the second and third estimation passes were assigned an Inferred category. In the second step, the automated classification was manually adjusted to remove isolated blocks and to define regular areas at the same resource classification. Isolated blocks were reclassified to the category of the surrounding blocks.
  • The mineral resources are reported in accordance with Canadian Securities Administrators' National Instrument 43-101 and have been estimated in conformity with generally accepted CIM Estimation of Mineral Resource and Mineral Reserves Best Practices Guidelines. Mineral resources are not mineral reserves and do not have demonstrated economic viability. There is no certainty that all or any part of the mineral resource will be converted into mineral reserve.

About Orezone Gold Corporation

Orezone is a Canadian company with a gold discovery track record of +12 Moz and recent mine development experience in Burkina Faso, West Africa. The company owns a 100% interest in Bomboré, the largest undeveloped gold deposit in the country that is situated 85 km east of the capital city, adjacent to an international highway. Mineral resources are constrained within optimized open pit shells that span 11 km, and include 4.13 Moz measured and indicated (125 Mt @ 1.03 g/t) and 1.03 Moz inferred resources (35 Mt @ 1.00 g/t) with an average drill depth of only 120 m. The Company is working to complete a definitive feasibility study in 2013 and become a mid-tier gold producer by 2015.

FORWARD-LOOKING STATEMENTS AND FORWARD-LOOKING INFORMATION: This news release contains certain "forward-looking statements" within the meaning of applicable Canadian securities laws. Forward-looking statements and forward-looking information are frequently characterized by words such as "plan," "expect," "project," "intend," "believe," "anticipate", "estimate" and other similar words, or statements that certain events or conditions "may" or "will" occur. Forward-looking statements in this release include statements regarding, among others, capital and operating cost estimates; gold production for the project; completion of a Definitive Feasibility Study in 2013; completion of a metallurgical test program in Q3/Q4 2012; completion of an additional resource update in Q1 2013; potential to significantly expand resources; commencement of production at the Bomboré Project in 2015; and generating sufficient cash flows from first phase of production on the Bomboré project to finance expansion.

FORWARD-LOOKING STATEMENTS are based on certain assumptions, the opinions and estimates of management at the date the statements are made, and are subject to a variety of risks and uncertainties and other factors that could cause actual events or results to differ materially from those projected in the forward-looking statements. These factors include the inherent risks involved in the exploration and development of mineral properties, the uncertainties involved in interpreting drilling results and other geological data, fluctuating metal prices, the possibility of project cost overruns or unanticipated costs and expenses, the ability of contracted parties (including laboratories and drill companies to provide services as contracted); uncertainties relating to the availability and costs of financing needed in the future and other factors. The Company undertakes no obligation to update forward-looking statements if circumstances or management's estimates or opinions should change. The reader is cautioned not to place undue reliance on forward-looking statements. Comparisons between any resource model or estimates with the subsequent drill results are preliminary in nature and should not be relied upon as potential qualified changes to any future resource updates or estimates.

Readers are advised that National Instrument 43-101 of the Canadian Securities Administrators requires that each category of mineral reserves and mineral resources be reported separately. Readers should refer to the annual information form of Orezone for the year ended December 31, 2011 and other continuous disclosure documents filed by Orezone since January 1, 2012 available at www.sedar.com, for this detailed information, which is subject to the qualifications and notes set forth therein.

Contact Information

  • Orezone
    Ron Little
    (613) 241-3699
    Toll Free: (888) 673-0663

    Pascal Marquis
    Senior V.P. Exploration
    (613) 241-3699
    Toll Free: (888) 673-0663