TORONTO, Aug. 28, 2011 /PRNewswire/ - Gran Colombia Gold Corp. (TSX: GCM) is pleased to announce drilling results from a further 51 drill holes totalling 18,009 metres from its diamond drilling program at the Marmato gold project in Colombia. These results, plus all previously announced results, will be reflected in an updated NI 43-101 mineral resource estimate, expected to be announced in the coming weeks.
The primary focus of the current infill drilling programme has been to increase the confidence in the Mineral Resource in the upper portions of the deposit, and to increase the confidence in the Inferred Resources at depth. The results of the current drilling indicate that a large amount of material previously categorised as Inferred Resource is likely to be converted into Indicated Resources.
The current infill drilling has also produced a number of intersections displaying higher grades at depth. These intersections show a slight change in the mineralisation style for the porphyry mineralisation, with a lack of veinlet mineralisation, but consistent grades over a number of samples, suggesting the possibility of a transitional or feeder zone to the main mineralisation. Further work is required by the Company to investigate the depth and strike continuity of these zones.
Highlights include hole MT-1398 which returned multiple economic mineralized intersections, with the best being 0.8 grams per tonne (g/t) gold and 2.8 g/t silver over 283 metres. Other highlights include hole MT-1414A, which returned 1.5 g/t gold over 92 metres. Significant results (greater than 20 gram-metres) are summarized below.
|Drill Hole #||From||To||Length||Au Grade||Ag Grade|
*denotes underground drill holes. The surface drill holes were inclined at -45 to -75 degrees from horizontal and the underground holes were drilled at -75 to +70 degrees from the horizontal, and the intersection lengths do not represent true widths. Sample lengths are normally 2.0 metres but may be varied for geological and recovery factors. Intersections were calculated using a cut-off grade of 0.1 g/t gold and no more than 6.0 metres of internal dilution. Gold grades were capped at 20.0 g/t and silver grades at 500 g/t.
The total number of metres drilled to date is 100,836 in 283 holes. A further 76 holes are planned of which 16 remain from surface to be drilled this year and 60 are planned from underground for completion by the end of March 2012. All of the results to date, together with a map showing the locations of the drill holes, are available on Gran Colombia's website at www.grancolombiagold.com.
The Marmato Project is the subject of a Technical Report prepared by SRK Consulting (UK) Ltd. announced on January 6, 2011 showing a measured and indicated mineral resource of approximately 226 million tonnes at an average gold grade of 0.9 g/t containing 6.6 million ounces of gold plus 116 million tonnes grading 0.9 g/t containing approximately 3.2 million ounces of gold classified as inferred resources at a cut-off grade of 0.3 g/t. Measured and indicated silver resources amounted to 37 million ounces plus a further 22 million ounces classified as Inferred resources based on silver grades of 5.1 and 5.9 g/t respectively. The complete Technical Report is available on sedar.com as well as the company's website.
SRK have also completed a Preliminary Economic Assessment, indicating that the preferred mining method is open pit with contractor mining. Based on processing 283 million tonnes of ore at a rate of 40,000 tonnes per day, production would average 340,000 ounces of gold and 1.3 million ounces of silver per year over a 21-year mine life. The cash operating cost is expected to be $524 per ounce of gold, net of silver credits. Assuming a life of mine capital cost of $550 million, total cost per ounce is estimated to be $643. Assuming gold and silver prices of $1,200 and $16 per ounce respectively, this method would result in a net present value of $1.1 billion assuming a discount rate of 5%. These estimates assume an average gold grade of 0.9 g/t, a stripping ratio of 3.3:1 and a metallurgical recovery of 88% for gold and 60% for silver. The complete Preliminary Economic Assessment is available on sedar.com as well as the company's website.
SRK are finalizing an updated mineral resource estimated expected to be announced shortly and Hatch & Associates have been retained to prepare a Pre-feasibility Study based on the updated resource estimate, the results of which are expected in the first quarter of 2012.
Stewart D. Redwood, Senior Consulting Geologist to Gran Colombia, is a qualified person as defined by National Instrument 43-101 and prepared or reviewed the preparation of the scientific and technical information in this press release in respect of the drilling results from the Marmato Project. Dr. Redwood verified the data disclosed in this press release, including the sampling, analytical and test data underlying the information contained in this release. Verification included a review of the quality assurance and quality control samples, and review of the applicable assay databases and assay certificates.
Quality Assurance and Quality Control
In the case of the drilling results referred to herein, the samples were prepared by Acme Analytical Laboratories Ltd (ISO 9001:2008) at their sample preparation facility in Medellin, Colombia, and were assayed at their laboratory in Santiago, Chile. Gold was assayed by fire assay with atomic absorption spectrophotometer ("AAS") finish. Samples over 10 g/t were assayed by fire assay with gravimetric finish. Silver was assayed by aqua regia digestion and AAS finish. Silver samples above 100 g/t were assayed by fire assay with gravimetric finish. Blank, standard and duplicate samples were routinely inserted for quality assurance and quality control.
About Gran Colombia Gold Corp.
Gran Colombia is a Canadian-based gold and silver exploration, development and production company with its primary focus in Colombia. Gran Colombia is currently the largest underground gold and silver producer in Colombia with six underground mines in operation. In addition, Gran Colombia is also developing a large-scale, open-pit gold and silver mine at Marmato. The Company also has a highly-prospective land position in Colombia as well as an advanced stage property in Venezuela and earlier stage properties in Mali. Additional information on Gran Colombia Gold can be found on the Company's website at www.grancolombiagold.com and by reviewing the Company's profile on SEDAR at www.sedar.com.
This news release contains "forward-looking information", which may include, but is not limited to, statements with respect to the future financial or operating performance of the Company and its projects. Often, but not always, forward-looking statements can be identified by the use of words such as "plans", "expects", "is expected", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates", or believes" or variations (including negative variations) of such words and phrases, or state that certain actions, events or results "may", "could", "would", "might" or "will" be taken, occur or be achieved. Forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of Gran Colombia to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Forward-looking statements contained herein are made as of the date of this press release and Gran Colombia disclaim, other than as required by law, any obligation to update any forward-looking statements whether as a result of new information, results, future events, circumstances, or if management's estimates or opinions should change, or otherwise. There can be no assurance that forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, the reader is cautioned not to place undue reliance on forward-looking statements.
SOURCE Gran Colombia Gold Corp.