May 4 2016
Continental Gold Inc. ("Continental" or the "Company") is pleased to announce positive final reconciled results from the trial mining program completed along the San Antonio vein in the Yaraguá vein system at the Buriticá project, Colombia. JDS Energy & Mining Inc. ("JDS") was retained to oversee the trial stope mining, processing of ore through Continental's small-scale milling facility and verification of all reconciled results.
Highlights (referenced in Figures 1, 2 and 3)
- The trial mining program results include 2,093 ounces of gold and 2,733 ounces of silver mined from 2,090 tonnes of mined material at an average grade of 31.1 grams per tonne gold and 40.7 grams per tonne silver, which is significantly greater than the 1,033 ounces of gold and 1,620 ounces of silver from 2,022 tonnes of material at an average grade of 15.9 grams per tonne gold and 24.9 grams per tonne silver that the current mineral resource model estimated would be mined;
- Initial stope design widths of 1.8 metres using the current resource model were increased in the final stope design to 2.3 metres prior to extraction, after channel sampling results indicated much wider mineralization due to intense veinlets intersecting the San Antonio vein at various orientations to strike (see Company press release dated February 4, 2016). This occurrence has been observed historically during development and mining at both the Yaraguá and Veta Sur vein systems, and indicates that delineation drilling and operational channel sampling may enhance the current mineral resource and mineral reserve grades for both deposits (see Company press releases dated January 7, 2015 and October 28, 2014);
- The trial mining, which included two adjacent, sequentially extracted stopes along the San Antonio vein, demonstrated the viability of mechanized long-hole mining, which is the primary method proposed in the February 24, 2016 Buriticá Project Feasibility Study; and
- Results validated that the Feasibility Study's stope design dimensions of 15 metres between sublevels and 30 metres along strike are viable without excessive ore loss or mining dilution. Also, rock fragmentation from blasting was excellent (Figure 3).
Details (referenced in Figures 1, 2 and 3)
In order to validate Feasibility Study mining method design criteria, JDS and the Company agreed that a trial mining test stope should be extracted from the Yaraguá deposit's San Antonio vein (Figure 1). JDS developed all test stope procedures to be used during extraction, including design methodology, engineering, survey requirements and long-hole mining methodology.
The two sequentially-extracted trial mining stopes were located within partially-oxidized rock approximately 80 metres below surface (1,545 RL to bottom sill sub-level); this was only 10 metres below the 70-metre weathered zone limit designated for cut-and-fill mining in the Feasibility Study (Figure 2). The San Antonio vein was selected for the trial mining stope because it is expected to contribute the most to future gold production from the Yaraguá system, and it is easily accessible from existing development as part of the Company's small-scale operating mine.
The trial mining stopes were designed based on the orientation and width of the San Antonio vein, as outlined in the most recent Yaraguá mineral resource block model prepared in accordance with Canadian National Instrument 43-101 ("NI 43-101"). The initial east stope design measured 11 metres drill height by 17 metres long by 1.8 metres wide, while the west stope measured 11 metres drill height by 12 metres long by 1.8 metres wide. The 1.8-metre width was determined by adding over-break of 0.3 metres to either side of the 1.2-metre-wide San Antonio vein.
Subsequent sublevel channel sampling in both stopes showed high-grade gold mineralization over substantially broader widths when compared to the modelled 1.2-metre average width of the San Antonio vein domain in this area of the mineral resource envelope; this is due to veinlet sets oblique to the main vein margins (see Company press release dated February 4, 2016).
Results are as follows:
To accommodate the broader-than-anticipated high-grade gold mineralization, the east and west final stope designs resulted in average widths of approximately 2.3 metres (including 0.3 metres over-break allowance for each stope side). From the 2015 Yaraguá mineral resource model, mill feed from the combined final stope designs was estimated to be 2,022 tonnes at 15.9 g/t gold.
Test-stope mining occurred in Q4 2015, with the milling of the mined material completed in Q1 2016. A total of 2,090 tonnes of mineralized material was milled, with final reconciled results compared to the planned stope design as follows:
Test-stope mining occurred in Q4 2015, with the milling of the mined material completed in Q1 2016. A total of 2,090 tonnes of mineralized material was milled, with final reconciled results compared to the planned stope design as follows:
Overall, the Company's trial mining program was a success; the trial mining clearly validated the Buriticá Feasibility Study design criteria and yielded the following conclusions:
- Long-hole mining is a suitable method for the majority of the Yaraguá and Veta Sur vein systems at maximum dimensions of 12-metre drilling distance and floor-to-floor sublevel spacing of 15 metres;
- Given that the trial mining was performed in a transition area between weathered and fresh rock, the long-hole mining method will be a viable option in marginal ground conditions during production;
- Test stope results validate the Feasibility Study's stope design dimensions without excessive losses or dilution (i.e., 15 metres between sublevels and 30 metres along strike);
- Ground control measures and safety protocols used during test stope development were adequate; and
- The higher-than-anticipated grades and widths, when compared to the mineral resource model, reinforce the importance of definition drilling and channel sampling for grade control in order to complete final stope designs during production.
Technical Information
Certain technical information in this press release is based upon information prepared by Gregory A. Blaylock, P.Eng. of JDS Energy & Mining Inc., a Qualified Person (as defined in the Canadian Institute of Mining, Metallurgy and Petroleum Standards on Mineral Resources and Reserves and NI 43-101) and independent of Continental.
The technical information in this press release has been reviewed and approved by Donald Gray, Chief Operating Officer of Continental, who is a Qualified Person under NI 43-101 standards.
Channel samples from the Yaraguá drift were prepared by ALS Colombia Limited of Medellín, Colombia and fire-assayed for gold and silver by ALS Perú S.A. of Lima, Peru, as well as assayed for other metallurgically-significant elements. Both ALS Colombia Limited and ALS Perú S.A. are independent of the Company. Process plant samples were prepared and assayed by SGS Colombia S.A.S. in Medellín, Colombia, which is independent of the Company. The Company utilizes a rigorous, industry-standard QA/QC program similar to that described in the Technical Report (defined below).
For additional information on the Buriticá project, please refer to the Feasibility Study technical report, prepared in accordance with NI 43-101, entitled "Buriticá Project NI 43-101 Technical Report Feasibility Study, Antioquia, Colombia" (the "Technical Report"). The Technical Report, with an effective date of February 24, 2016 and dated March 29, 2016, was prepared for the Company by JDS. A copy of the Technical Report can be accessed under the Company's SEDAR profile at www.sedar.com, or on the Company's website at www.continentalgold.com.
Source: http://www.continentalgold.com/en/