The Bigstone deposit is located within the Northern Lights Property, which lies west of McIlvenna Bay. Bigstone is Foran’s second NI 43-101 compliant deposit within the Hanson Lake District. Its initial resource estimate was announced in December 2020 and the Technical Report on the Bigstone Project (Amended) was filed on February 1, 2022 (2020 Resource Estimate).
Grading 2.22% Copper Equivalent:
81.9 million lbs Cu
40.2 million lbs Zn
16,000 oz Au
603,000 oz Ag
Grading 2.14% Copper Equivalent:
55.9 million lbs Cu
114.4 million lbs Zn
19,000 oz Au
729,000 oz Ag
Foran drilled one of the longest mineralized intercepts in the region during its program in 2015, which returned 105m of 2.03% copper.
Location and Infrastructure
Bigstone is accessible via helicopter, boat or winter road.
Winter road access is 103 km from Flin Flon along Saskatchewan Provincial Highway 106 and 17 km south on a winter access trail. The Bigstone deposit lies approximately 25 kilometres west of Foran’s McIlvenna Bay deposit and is accessible in winter from Foran’s Hanson Lake exploration camp via a 51 km gravel road, highway 106 and winter roads.
Foran owns a 100% interest in the Bigstone Property. Some of the claims that make up the property are subject to a 2% NSR.
The Bigstone deposit is hosted by a north trending, steeply dipping and west facing succession of volcanic and subvolcanic intrusive rocks and minor sediments. Mineralization at the Bigstone deposit is represented by three zones of mineralization: a laterally extensive zinc-rich massive sulphide horizon, a copper-rich feeder zone which underlies the massive sulphide and a peripheral zinc-rich halo associated with portions of the copper zone.
The zinc-rich massive sulphide horizon averages 5m thick and has been defined by drilling over a strike length of 400m. The massive sulphide mineralization is dominated by massive to semi-massive pyrrhotite and/or pyrite with abundant red sphalerite.
The Copper Zone tends to be located approximately 20m stratigraphically below the massive sulphide in a zone of strong chlorite alteration and silicification. The copper zone occurs as a vertically oriented, flattened cylindrical body that has been drill tested in part between 100m and 600m below surface. It is interpreted to be a sub-seafloor replacement body that represents a feeder zone to the massive sulphide mineralization. The Copper Zone mineralization dominantly consists of chalcopyrite, pyrrhotite, pyrite +/- magnetite that occurs in a combination of semi-massive, disseminated and stringer styles.
The zinc stringer zone occurs peripheral to portions of the copper zone and generally occurs as sphalerite-rich stringers with lesser pyrrhotite, pyrite and/or chalcopyrite in bleached and silicified volcanic rocks.
The Bigstone deposit has been defined by approximately 24,000m of drilling (55 holes with 24 wedges) since it was first discovered in 1982 with the majority of the drilling completed between 1982 and 1984. Subsequent programs generally focused on large step-outs along strike and depth. Due to this focus, the absolute limits of the mineralization have not been fully defined by historic drilling and as a result the deposit remains open for expansion.
Estimation Methodology and Parameters
Eleven mineralized domains were defined representing the three zones of mineralization:
- Copper Zone – Three wireframes have been modelled to approximately 600m below surface, extending <50m to approximately 200m along strike, with thickness ranging from less than one metre to greater than 50m, with an average thickness of 17.7m
- Zinc Stringer Zone – Seven wireframes have been modelled with individual strike lengths ranging from 75m to 200m along strike and 50m to 350m down dip. Thickness range from less than one metre to greater to approximately five metres thick, with an average thickness of 5.2m.
- Massive Sulphide Zone – Single wireframe comprising high grade zinc which stratigraphically overlays and overlaps the Copper Zone and Zinc Stringer Zone. The zone is variable in thickness with intersections from less than one metre to greater than 15m and an average thickness of 5.9m.
The Mineral Resource estimate was based on a database comprised of 95 drill holes, of which 55 intersected resource domains. The data was parsed and validated for modelling in Leapfrog Geo/Edge software with the interpretations constrained to the geology where necessary. Capping was performed for each metal by domain and composited to one metre lengths. Resource domains were used to constrain the grade interpolation, which was estimated with inverse distance squared using three passes for the Massive Sulphide Zone, and a single pass for the Copper and Zinc Stringer Zones. Grades were estimated into a rotated block model with two metre x two metre x two metre sized blocks, sub blocked to 0.5 metres. Mineral Resource classification is based on the drill hole spacing as well as the Qualified Person’s level of geological knowledge and confidence.
As the polymetallic sulphide mineralization at the Project contains significant copper, zinc, silver, and gold values, block grade was converted into NSR values ($ per tonne). The NSR values account for parameters such as metal price and US dollar exchange rate, metallurgical recoveries, smelter terms and refining charges, and transportation costs. The Mineral Resource estimate was reported within resource shapes generated in Deswik Stope Optimizer software, satisfying continuity criteria, and using an NSR cut-off values of US$65/t on a block basis.
The 2020 Bigstone Resource Estimate meets the guidelines as set out in CIM (2014) definitions for mineral resources and the work was completed by Roscoe Postle Associates Inc. (“RPA”), now part of SLR Consulting Ltd. The 2020 Bigstone Resource Estimate was verified by Ms. Katharine Masun, P.Geo. Ms. Masun is a Qualified Person as defined in NI43-101 and has consented to applicable disclosure contained herein regarding the 2020 Resource Estimate.