Reports New Resource Estimate At Lorraine, Resulting In A Significant Increase To Total Copper-Gold Resource Base
NorthWest Copper (TSX-V: NWST) (OTCQX: NWCCF) is pleased to announce a new updated independent, Mineral Resource Estimate (“MRE”) for its Lorraine property (the “Lorraine Project”), located approximately 280km northwest of Prince George, BC and approximately 40km from the Company’s Kwanika-Stardust Projects. The MRE has an effective date of June 30, 2022 and is based on historical drilling from 1949 to 2009. Details of the MRE are shown in Table 1.
Differences may occur in totals due to rounding
The updated MRE is based on “reasonable prospects for eventual economic extraction” and is constrained in a Lerchs Grossman (LG) open pit shell that was constructed using $US3.50/pound for Cu and $US1,650/ounce for Au. The Lorraine Project has multiple characteristics that are positive for potential future development:
“This updated Mineral Resource Estimate adds to our overall copper-gold resource base with both size and good grades close to surface,” said President and CEO Peter Bell. “Our portfolio continues to deliver results and the proximity of Lorraine to our flagship Kwanika-Stardust Projects is significant. We have just begun our work at Lorraine and look forward to our planned first drilling program later this summer.”
The Lorraine Project
The Lorraine Project is located in central British Columbia, 280km northwest of Prince George, BC and approximately 40km from NorthWest’s Kwanika-Stardust Projects (Figure 1), with favourable topography between the deposits. The Lorraine Project covers 56,000 hectares of ground, while the area containing the MRE at the 0.20% copper cut-off is 42.1 hectares in size and has a footprint of about 1.8 km by 0.5 km (Figure 9).
The Lorraine Project deposit is a silica-undersaturated alkalic copper-gold porphyry deposit, which is the same classification as the Galore Creek and Mount Polley deposits 3 . Mineralization at the Lorraine Project is hosted by Early Jurassic syenite, monzonite, and pyroxenite intrusions that are part of the Duckling Creek Syenite Complex (“DCSC”). At least 20 exploration targets have been identified across the DCSC by past geological, geochemical, and/or geophysical surveys, however drilling on these prospects is either absent or very limited.
The MRE at the Lorraine Project extends to surface and includes the historical Lower Main, Upper Main, and Bishop Zones and intervening rock (Figures 2-7). Copper sulphides manifest various combinations of chalcopyrite, bornite and chalcocite, and the concentration of pyrite is relatively low. Gold is spatially related to the copper mineralization, and elevated concentrations of palladium have been reported in several published papers.
The Company has a strategic drilling program planned for 2H 2022 in the MRE area at the Lorraine Project to increase the understanding of the deposit. Additionally, there is a large amount of historical data that is currently being analyzed, including historical drill core that is being relogged. Moving forward the Company plans to use this data to increase the geological understanding of the project and target new areas for exploration.
The MRE is exclusive to the certain portions of the Lorraine Project (Bishop, Lower Main and Upper Main) and does not include the nearby Top Cat mineral claims.
About The MRE
The updated Lorraine MRE was prepared by Mr. Michael Dufresne, M.Sc., P.Geol., P.Geo. President and Principal of APEX Geoscience Ltd. (APEX) and an independent Qualified Person (QP) with assistance from Mr. Deon Van der Heever of RockRidge Partnership & Associates with an effective date of June 30 2022. Mr. Dufresne takes responsibility for the MRE, which replaces the previous historic Lorraine mineral resource estimate. The MRE was prepared in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) and CIM Definition standards (2014) . The database for the Lorraine Project contains 398 drillholes representing 63,445.03 meters of drilling. Grade estimation in the MRE is based on 167 drillholes and 25,506.42 meters of drilling. Of this, 23,226.51 meters was in 143 diamond drill holes and 2,279.91 meters in 24 percussion drill holes. Drill Hole spacing is generally less than 50m in densely drilled portions of the project with a plan view showing the drill hole locations in the resource boundary domain is in Figure 10. The MRE incorporates geological and structural constraints developed through lithological and structural modeling as well as familiarity of the deposit by NorthWest’s geologists. An optimized pit shell further constrains the MRE volume to fulfil the requirement for “reasonable prospects for eventual economic extraction” and the assumptions are outlined below:
For grade estimation, 3 m composites were created within the domain boundaries using the best-fit method. Capping values on composites were used to limit the impact of outliers. Copper was capped at 2.95%, 2.00% and 2.78% for the Bishop, Lower Main, and Upper Main Zones, respectively. Gold values were capped at 0.80 g/t, 1.00 g/t and 2.50 g/t for the Bishop, Lower Main, and Upper Main Zones, respectively. Block tonnes were estimated using 2.70 g/cm for mineralized material.
The block model was created using 20 m x 20 m x 5 m blocks in the X, Y and Z directions. To honor the volumes, the model was sub-blocked to 5 m x 5 m in the X and Y direction and truncated against domain boundaries in the Z direction. Sub-blocks retained the grade of the parent block. Grades were estimated with ordinary kriging and anisotropic search orientations along mineralized trends. Three estimation passes were used, whereby each successive pass utilized a less restrictive sample search strategy for block estimation. Search radii for the first estimation pass equals half of the variogram range. The second pass increases the search distance to the variogram range, and the third pass further expands to more than twice the variogram range.
The block model was classified into Indicated and Inferred Mineral Resource categories. Blocks were assigned a preliminary classification based on the variography, drillhole spacing, domain and number of samples used in the estimation of each pass. The Indicated category consists of blocks estimated in the first pass with the range being half of the variogram distance. Blocks estimated in the second pass employed a search distance of the full variogram range and were allocated to the Inferred Resource category. Blocks that were estimated in the third pass with the more relaxed search parameters were also assigned to the Inferred Mineral Resource category.
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