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Refocus 2021 drilling on environmental, geotechnical data North of 60 Mining News – October 15, 2021
Constantine Mining LLC Joint Venture completed 2,917 meters of infill, environmental, and geotechnical drilling during the 2021 program at the Palmer VMS project.
The geotechnical and environmental data collected this year is applicable to a permit that will allow Constantine Mining LLC JV to begin the development of a proposed underground exploration ramp at Palmer.
Constantine Metal Resources Ltd. Oct. 14 reported initial assay results from a 2021 summer work program at Palmer that primarily focused on geotechnical and environmental drilling to support a planned underground exploration program and feasibility-level studies for this polymetallic volcanogenic massive sulfide project in Southeast Alaska.
According to the most recent calculation, the South Wall and RW zones at Palmer host 4.68 million metric tons of indicated resource averaging 5.23% (539 million pounds) zinc, 1.49% (154 million lb) copper, 30.8 grams per metric ton (4.6 million ounces) silver, 0.3 g/t (451,000 oz) gold and 23.9% (1.12 million metric tons) barite; plus 9.59 million metric tons of inferred resource averaging 4.95% (1.05 billion lb) zinc, 0.59% (124 million lb) copper, 69.3 g/t (120.6 million oz) silver, 0.39 g/t (21.4 million oz) gold and 27.7% (2.65 million metric tons) barite.
A 2019 preliminary economic assessment outlined plans for a 3,500-metric-ton-per-day mill at Palmer that would produce 1.07 billion lb of zinc, 196 million lb of copper, 18 million oz of silver, 91,000 oz of gold, and 2.89 million metric tons of barite over an initial 11-year mine life.
Funded by Dowa Metals & Mining Alaska Ltd., Constantine's joint venture partner at Palmer, this year's US$8.8 million program was originally expected to involve roughly 6,000 meters of exploration, resource upgrade, and geotechnical drilling.
Drill contractor staffing issues and low drill productivity, however, caused the company to refocus the drilling to ensure that the geotechnical and environmental aspects of the program were completed.
As a result, eight diamond holes for a total of 2,917 meters were drilled.
This includes two infill and hydrological holes drilled into the lower reaches of South Wall, which hosts the bulk of the resources and is where mining is expected to begin.
Constantine has received assay results from the first of these holes, CMR21-143B, which cut zones of semi-massive to massive sulfides and barite intervals in an area of inferred resources in the lower part of South Wall.
From a drilled depth of 451.2 meters, this hole cut 36.9 meters averaging 0.16% copper, 2.16% zinc, 16.68 g/t silver, 0.09 g/t gold, and 17.5% barite.
This hole cut a second, shorter but higher-grade intercept. Starting at 504.8 meters, this 6.9-meter intercept averaged 2.1% copper, 7.08% zinc, 40.57 g/t silver, and 0.42 g/t gold.
Constantine reports that the second infill hole, CMR21-144, cut chert and footwall stringer mineralization near the Kudo fault at the bottom of the South Wall zone. Assay results are pending.
In addition to the infill drilling, another six geotechnical diamond holes were completed in the Palmer deposit area to provide hydrological information, including water volume and water quality. Monitoring wells were completed in five of them.
Besides drilling, Constantine reports that extensive geotechnical, engineering, and environmental studies were carried out during the 2021 field season. This work to prepare for developing an underground exploration ramp and engineering studies for a planned future mine included:
• A 6.7-line-kilometer seismic survey in Glacier Creek valley to collect depth to bedrock information.
• A 12-holes sonic overburden drill program in Glacier Creek valley to determine the overburden stratigraphy, establish bedrock depths, and provide hydrological information from groundwater monitoring wells.
• Updates to the avalanche study database were completed and will further aid in designing avalanche mitigation requirements and safe locations for project infrastructure.
• A review of the exploration portal access road to provide an updated cost estimate to upgrade the switchback road to the portal site to a 10-12% grade in 2022, in preparation for the 2023 planned start of the underground exploration ramp.
• Three Glacier Creek monitoring stations were established to provide seasonal stream flow information, particularly for difficult to acquire high-energy flows during peak periods.
• Two weather stations are established to provide continuous temperature, precipitation, and wind information.
Constantine says the geotechnical and environmental information collected this year and previous seasons is applicable to an amended Waste Management Permit application to be submitted in the first quarter of 2022. When approved, this permit will allow Constantine Mining LLC Joint Venture to begin planned underground exploration during the summer of 2023. This underground exploration program is expected to take 18 months to complete and will provide access to the hanging wall of the lower South Wall deposit for resource upgrade and confirmation of geological, hydrological, and geotechnical information currently being collected from surface drill holes.
A program of surface resource upgrade drilling and exploration drilling at the South Wall and RW zones, as well as the nearby AG deposit, is being considered while the underground preparation and development work takes place. Any additional geological, geotechnical, and hydrological information completed up to 2024 will provide necessary data for permitting and feasibility level studies that determine future mine development at Palmer.
Over his more than 16 years of covering mining and mineral exploration, Shane has become renowned for his ability to report on the sector in a way that is technically sound enough to inform industry insiders while being easy to understand by a wider audience.
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