Silvercorp Reports High-Grade Mineralization Discovery Below Current Production Levels Within Major Vein Structures at GC Ag-Pb-Zn Mine in Guangdong Province
In 2016 and 2017, the Company launched extensive exploration program and completed a total of 33,029 meters (“m”) of underground diamond drilling and 19,619 m of exploration tunneling at its GC Ag-Pb-Zn mine. Significant high-grade mineralized zones have been exposed at and below the current production levels, and major mineralized zones have been extended along strike and downdip.
The drilling program included infill drilling to define and upgrade the current resource model, and step-out drilling for new resources surrounding and below the current resource area. Between 2016 and 2017, 294 NQ sized diamond drill holes with total length of 33,029 meters were accomplished at 7 production levels from 150 m to -200 m at 50 m interval (the elevation of the head frame is 258.5 m). Among them, 153 holes intersected ore veins with Ag equivalent (AgEq) values greater than 194 g/t, and another 36 holes hit mineralized veins with AgEq values between 97 and194 g/t (Tab. 1).
Table 1: Summary of the drilling programs in 2016 and 2017
|Year||Meters Drilled||Holes Completed||Samples Collected||Holes Intercepted |
|Holes Intercepted |
In 2016 and 2017, 19,619 m of tunneling were driven along and across the major mineralized vein structures to upgrade the resource model and test for new vein structures. These included 7,767 m key drifts that exposed 4,803 m of ore veins, as well as 4,351 m of key raises that exposed 3,002 m of ore veins (Tab. 2).
Table 2: Summary of the tunneling programs in 2016 and 2017
|Year||Tunneling (m)||Samples Collected||Key Drifts Included (m)||Ore Exposed in Drifts (m)||Key Raise Included (m)||Ore Exposed in Raises (m)|
Tables 3 and 4 below list assay results of some selected drill holes that intercepted ores and drift tunnels that exposed ore zones in the 2016 and 2017 exploration programs.
Table 3: Selected drilling results from the 2016 and 2017 drilling programs at GC mine
|Year||Hole ID||From |
|True Width |
|AgEq (1,2) |
(1) Metal prices assumed: Ag USD19/Oz, Pb USD1.0/lb., Zn USD1.2/lb.
(2) Ag equivalent AgEq = Ag grade (g/t) + 53.9 x Pb grade (%) + 50.5 x Zn grade (%)
Table 4: Selected drifts that exposed ore zones at GC mine in 2016 and 2017
|Drift ID||Vein||Elevation |
The step-out drilling and tunneling in the east of the mine defined new mineralized vein structures including V7E、NV10、V14、V19、V31、V32 and V33. Vein V7E has been defined 95 m in strike length, 150 m in downdip length and 0.8-1.75 m in width, with average grade of 81 g/t Ag, 1.43 % Pb and 3.08% Zn. The exploration program at -150m and -200m levels indicated that the length and width, ore continuity and ore grades improved greatly with the increase of depth (Tab. 5).
Table 5: Increases of average grades in veins V2E and V2W with depth
|True Width |
In addition, two drill holes, 18CK26A04 and 18CK28A05, hit high-grade mineralization with true width of 3.31 m and 1.97 m, respectively, at elevation around -455 m. The host rock of the mineralization is slate, which indicated that the mineralization system is not limited to granite, but extend into the sedimentary rock underneath the granite intrusive. Also, the trend of increasing Ag, Pb, Zn and Cu grades with depth continued to below -450 m elevation. The assay results of the intercepted ore of drill hole 18CK28A05 are 310 g/t Ag, 2.13% Pb, 14.96% Zn, 0.73% Cu, 0.19% Sn and 0.34 g/t Au.
Drill core samples were taken from sawn half core for every 1.5m or limited by apparent wall rock and mineralization contact. Half of the core was sent to the laboratory for analysis and the other half retained for archive. The channel samples are collected along sample lines perpendicular to the mineralized vein structure in exploration tunnels. Sample length ranges from 0.2 m to more than 1.0 m, depending on the width of the mineralized vein and the mineralization type. Spacing between sampling lines is typically 5 m along strike. Both the mineralized vein and the altered wall rocks are cut with continuous chisel chipping. The samples are individually secured in cotton sample bags and then collectively secured in rice bags for shipment to the on-site laboratory.
For analysis, the sample is dried and crushed to minus 1 mm and then split to a 200-300 g subsample which is further pulverized to minus 200 mesh. A duplicate sample of minus 1 mm is made and kept at the laboratory archives. Two subsamples are prepared from the pulverized sample. One is digested with two-acids for analysis of silver, lead, zinc and copper with AAS. The other is retained as pulp reject at the lab for future reference.
A routine quality assurance/quality control (QA/QC) procedure is adopted to monitor the analytical quality at the lab. Certified reference materials (CRMs), pulp duplicates and blanks are inserted into each lab batch of samples. QA/QC data at the lab are attached to the assay certificates for each batch of samples.
The Company maintains its own comprehensive QA/QC program to ensure best practices in sample preparation and analysis of the exploration samples. Project geologists regularly insert CRM, field duplicates and blanks to each batch of core samples to monitor the sample preparation and analysis procedures at the labs. The analytical quality of the labs is further evaluated with external checks by sending about 3-5% of the pulp samples to higher level labs to check for lab bias.
Data from both the Company's and the lab’s QA/QC programs are reviewed on a timely basis by project geologists.
Guoliang Ma, P. Geo, Silvercorp’s Manager of Exploration and Resource, reviewed the exploration data and prepared the scientific and technical information regarding exploration results contained herein. He is the Qualified Person on the project as defined under National Instrument 43-101 and has verified and approved the contents of this news release.
Silvercorp is a low-cost silver-producing Canadian mining company with multiple mines in China. The Company's vision is to deliver shareholder value by focusing on the acquisition of under developed projects with resource potential and the ability to grow organically. For more information, please visit our website at www.silvercorp.ca.
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