Roxgold announces an updated mineral resource estimate for the 55 Zone ahead of upcoming PEA study
TORONTO, Aug. 27, 2013 /CNW/ - Roxgold Inc. ("Roxgold" or "the Company") (TSXV: ROG) is pleased to announce an updated resource estimate for the 55 Zone deposit located on its 100% owned Yaramoko exploration permit in Burkina Faso. The resource estimate is based on 99,077 metres of drilling and was prepared by AGP Mining Consultants Inc. ("AGP") in accordance with National Instrument 43-101 ("43-101") Standards for Disclosure of Mineral Properties. Roxgold is currently completing a Preliminary Economic Assessment ("PEA") on the 55 Zone that will demonstrate a potential economic case for extraction of gold at the 55 Zone.
- An Indicated Resource of 850,000 gold ("Au") ounces estimated using a 3.0 gram per tonne ("gpt") cut-off grade - a 143% increase in ounces compared to the Maiden resource estimate dated August 7, 2012*
|Table 1. Q3 2013 Resource Estimate Summary|
|Resource at August 26, 2013|
|Category||Cut -off gpt||Tonnes||Au gpt||Au Oz|
"This is an encouraging step forward for Roxgold, as it provides us with a solid foundation on which to build," stated John Dorward, President and CEO of Roxgold. "The first leg of our strategy was to grow the deposit and illustrate the potential for increases above the initial 350,000* ounces within the indicated category. In just over a year, we have successfully delivered on this, increasing the ounces in the indicated category to 2.4 times the original estimate. In addition to this growth, the deposit remains open to future potential expansion at depth. I consider that this achievement places Roxgold in a strong position as we close in on completing the PEA. "
*Refer to Company disclosure on Company's website dated August 7, 2012
Table 2 provides a comparison between the August 27, 2013 resource estimate, the March 2013 resource estimate, and the August 2012 resource estimate. The table also provides the sensitivity of the deposit using cut-off grades of 3.0 gpt Au and 5.0 gpt Au.
Table 2. August 27, 2013 Resource Estimate Compared to Previous Estimates
|Resource Update Aug., 2013||Resource Update Mar., 2013||Maiden Estimate Aug., 2012|
|Category||Tonnes||Au gpt||Au Oz||Tonnes||Au gpt||Au Oz||Tonnes||Au gpt||Au Oz|
|*2013 43-101 resource estimate published at a 3.0 gpt cut-off|
|** 2012 43-101 resource estimate published at a 2.0 gpt cut-off.|
Roxgold has progressed the first leg of its three-point strategy with the growth in ounces at the 55 Zone and is working toward the completion of the second leg, completing a PEA. In addition, the Company is continuing a systematic regional exploration program across the 167km2 Yaramoko permit.
Roxgold's regional exploration is ongoing and the Company is currently drill testing targets defined through auger and IP (Induced Polarization) surveys earlier in the year. These targets include Bagassi South, 55 West, the 117 Zone and the 109 Zone.
Yaramoko, Roxgold's 100% owned exploration concession, contains several documented occurrences of gold mineralization. The most prominent of these is the high grade 55 Zone deposit. The 55 Zone is a shear zone hosted gold deposit that occurs along an east-west trending shear within a granitic host rock. Mineralization modelled within the 55 Zone occurs within a discreet shear zone averaging 3.23 metres horizontal width and ranging from 0.2m through to 17.0m. Mineralization is typically associated with quartz veining and pyrite mineralization. The 55 Zone has been identified to date to have a surface strike length of 750 metres and has been intercepted in drilling to 900 metres vertical depth. The maiden resource on the 55 Zone was announced by the Company on August 7, 2012.
AGP was commissioned by Roxgold to undertake the mineral resource estimate for the 55 Zone. Mr. Pierre Desautels (B.Sc. P.Geo) of AGP has been responsible for the initial resource estimate and the current estimate presented here today along with Mr. Lyn Jones of AGP who oversaw metallurgical testing. There was close collaboration between Mr. Desautels, Roxgold personnel and other technical consultants engaged by Roxgold. Mr. Desautels has completed two site visits to the Yaramoko concession, most recently in January 2013, and has attended multiple meetings with Roxgold technical staff at the Roxgold offices in Toronto. On these site visits Mr. Desautels has been able to observe all operations conducted by the Company from drilling to the dispatch of samples to the lab and has been able to observe the diamond drill core in person.
Resource modelling was based on Roxgold's database as of the June 20, 2013. The database was audited by Taiga Consulting Ltd, which maintains the Company's database.
MINERAL RESOURCE ESTIMATE PARAMETERS AND METHOD
The block model mineral resources were estimated for the 55 Zone of the
Yaramoko permit. The estimate encompasses the main vein and three
smaller accessory veins located on the footwall of the main vein. The
estimate was completed based on the concept of an underground
operation. No other zones on the Yaramoko permit were evaluated.
The three-dimensional (3D) wireframe model was primarily based on the
width of the deformation zone, typically taking into account grade in
excess of 2.0 gpt with exception made for continuity, lithology,
alteration and structure. Assays down to 1.0 gpt were added to the
wireframe if they were immediately adjacent to the mineralized zone and
in favourable lithologies. Intervals shorter than 1.5 metres
horizontally were expanded to account for a 1.5 metre horizontal
minimum mining width. The 3D wireframe describes the shape of the
mineralized horizon. The grade boundaries with the hanging wall and
footwall waste are both sharp.
Results of the gravity/cyanidation tests for the granite composite
indicated 90% Au recovery to the gravity concentrate, and an 87% Au
stage recovery from the gravity tailings by cyanide leaching, for a
combined gravity + cyanidation gold recovery of close to 99%. Results
for the mafic volcanic composite were slightly lower, with a 61%
recovery to the gravity concentrate and an 85% Au stage extraction
during cyanidation with a combined gold extraction achieving 94%
overall. Direct cyanidation leach tests indicated that for both
composites, high gold extractions (>95%) are achievable by this method.
A follow up test work program was completed in July 2013, on new
composite samples from the Yaramoko Zone 55 Main deposit with results
A (3D) geological and block model was generated using GEMS(c) software.
The block model matrix size of 2 x 5 x 5 metres (width x length x
height) was selected with consultation with the engineering team from
AGP and was based on the size that was deemed suitable for an
underground narrow vein mining scenario.
The model was interpolated with 243 holes totalling 99,077 metres of
drilling completed by Roxgold from mid-2011 through to June 20, 2013.
All drill holes are diamond drill core sampled at approximately 1-metre
intervals within the mineralized zone. The composite interval selected
was 1.5 metres down hole with composite remnants backstitched to the
The previously applied capping strategy was retained for this model
update. For the treatment of outliers, raw assays were capped to 250
gpt Au in combination with a search restriction applied on composites
values greater than 75 gpt Au. The procedure used allows the deposit to
retain the high grade assays while limiting their influence during the
interpolation to a maximum of 10m x 30m x 25m (width x length x
height). The impact to the resource amounted to an 8.4% reduction to
the total Indicated and Inferred ounces estimates at a 3.0 gpt cut-off.
Densities were determined from 4,336 representative rock samples using
industry standard methods. For the Main zone a density of 2.78
tonnes/metre3 was applied to the model using the density of each lithology within the
55 and 55 Footwall Zone.
Obtaining a valid variogram for a narrow vein, high grade deposit is
typically difficult. Due to issues encountered in obtaining a
reasonable variogram, inverse distance cube methodology was retained
for the grade interpolation of this resource estimate update. The
interpolated Krige model was used for validation as well as a nearest
neighbour check model.
The interpolation was carried out in multiple passes with increasing
search ellipsoid dimensions. Classification for all models was based
primarily on the pass number followed by an adjustment to the class
model, based on a diamond drilling density (core area) and the distance
to the closest sample.
Underground mine plans have been examined as part of the PEA and will be
described in the forthcoming PEA.
Mineral resources that are not mineral reserves do not have demonstrated
Under CIM definitions, Mineral Resources should have a reasonable
prospect of economic extraction. In order to assess the Mineral
Resources an insitu resource cut-off grade of 3.0 gpt gold was applied
based on a gold price of US $1,400 per troy ounce.
The quantity and grade of reported inferred resources in this estimation
are conceptual in nature and there has been insufficient exploration to
define these inferred resources as an indicated or measured resource
and it is uncertain if further exploration will result in upgrading
them to an indicated or measured resource category.
Rounding of tonnes as required by reporting guidelines may result in
apparent differences between tonnes, grade and contained metal content.
A number of collar positions were validated during the site visit using
a hand held GPS. Assays were validated against the original
certificates obtained directly from the issuing laboratories.
Pierre Desautels, P.Geo, and Mr. Lyn Jones P. Eng. of AGP Mining Consultants Inc., are Qualified Persons within the meaning of National Instrument 43-101 who are independent consultants to the Company, have verified and approved the data disclosed in this release. This includes the sampling, analytical and test data underlying the information.
Quality Assurance/Quality Control
Drill holes incorporated in this resource update were drilled using HQ and NQ sized diamond drill bits. Company personal are located at the drill site. Contractors and employees of Roxgold conducted all logging and sampling. The core was logged, marked up for sampling using standard lengths of two metres outside of the "zone" and adjusted to lithological contacts up to one metre within the "zone". Samples are then cut into equal halves using a diamond saw. The left half of the core remained in the original core box and stored in a secure location at the Roxgold camp within the Yaramoko area. The other half was sampled, catalogued and placed into sealed bags and securely stored at the site until it was shipped to Act Labs in Ouagadougou ("The Lab"). The core was dried and crushed by The Lab and a 150 gram pulp was prepared from the coarse crushed material. The Lab then conducted routine gold analysis using a 50 gram charge and fire assay with an atomic absorption finish. Samples within the 55 Zone or samples returning over 5 grams per tonnes are additionally assayed using a metallic screen analysis in which a 1000 gram pulp is analyzed. The screening of samples produced two size fractions - less than 100 micrometres (um) and greater than 75 um. These fractions are then analyzed independently by fire assay and atomic absorption. Quality control procedures included the systematic insertion of blanks, duplicates and sample standards into the sample stream. In addition, The Lab inserted their own quality control samples.
Roxgold is a TSX.V listed exploration and development company with its key asset, the 167 Km2 Yaramoko permit, located to the south of and contiguous to SEMAFO's Mana Project in the Houndé region of Burkina Faso, West Africa. Roxgold is focused on further exploring the Company's 100% owned Yaramoko permit and advancing the 55 Zone.
Forward Looking Statements
This news release may contain forward-looking statements. These statements are based on information currently available to the Company and the Company provides no assurance that actual results will meet management's expectations. Forward-looking statements in this news release include statements that describe the Company's future plans for the exploration and development of the 55 Zone and regional exploration in 2013, the potential of the 55 Zone including its prospectivity at depth and the extensions of the mineralized area at depth, the objectives or goals of exploration programs, and timing of future announcements, and include words to the effect that the Company or management expects a stated condition or result to occur. Forward-looking statements may be identified by such terms as "anticipates", "believes", "could", "estimates", "expects", "may", "shall", "will", or "would". Forward-looking statements are based on assumptions and address future events and conditions; by their very nature they involve inherent risks and uncertainties. The assumptions upon which forward looking statements in this news release are made include the reasonable assumptions of management with respect to the geologic model, that third party labs will continue to process assays at the current pace, results of exploration will warrant further work, and current macro-economic conditions will continue to prevail. Actual results relating to such future events and conditions could differ materially from those currently anticipated in such statements for many reasons such as: changes in management, changes in general economic conditions and conditions in the financial markets; changes in demand and prices for minerals; litigation, legislative, environmental and other judicial, regulatory, political and competitive developments and other matters discussed in this news release. This list is not exhaustive of the factors that may affect any of the Company's forward-looking statements. These and other factors should be considered carefully and readers should not place undue reliance on the Company's forward-looking statements. The Company does not undertake to update any forward-looking statement that may be made from time to time by the Company or on its behalf, except in accordance with applicable securities laws.
Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.
SOURCE Roxgold Inc.For further information:
John Dorward, President and CEO