The Woodjam property is located in British Columbia, Canada, 45 kilometres east of Williams Lake and cover to the small town of Horsefly (so named because of the ubiquitous biting insects). It is owned by Vizsla Copper. The project area covers the boundary between two very different types of rock; the ancient volcanic ocean islands that make up the Nicola Arc and a large intrusive Takomkane batholith to the east. Unusually for a porphyry property it displays multiple styles of mineralization in close proximity, and even more unusually it has been the subject of a major joint venture since 2010 and is very well studied.
Discovery
The region has been explored for gold since the Cariboo gold rush with the town of Horsefly dating back to 1859. However it has only been in the latter half of the 20th Century that the area has actively been explored for copper with the discovery of the Mount Polley and the Gibraltar Deposits to the north. The property itself was looked at by various operators since the 1960’s but the over 100m of till (rock and clay mixed and dropped by the glaciers) defeated all attempts. Initial work located strong but limited mineralization in 2004 such as 274 m of 0.14% Copper and 1.03 g/t Gold. Finally in 2007 drilling a blind subsurface IP target in the southeast hit 242.6 meters grading 0.18% copper and 64 ppm molybdenum and proved the existence of a large buried porphyry system, the Southeast Zone.
Delineation and Drilling
Since 2010 the project has been developed with Gold Fields Ltd. which is one the world’s largest gold producers. Highlights of the drilling since discovery include 0.69% Cu, 0.26 g/t Au and 0.006% Mo over 359.1 m, including 1.01% Cu, 0.44g/t Au and 0.002% Mo over 200.8 m and a 2013 resource was calculated at 227 MT of 0.31% Copper for the Southeast Zone. In addition two other zones the Takom and Deerhorn zones have resources of 8.3 MT of 0.26 g/t Gold 0.22% Copper and 32.8 MT 0.49 g/t Gold 0.22% Copper respectively.
Drilling has tapered off somewhat since the property was sold in 2015, but Visla’s 2020-2021 drill program has also been successful, with results such as 110 m at 0.44% copper and 2.57 g/t gold from the Deerhorn deposit suggesting the potential for relatively gold-rich porphry.
Grades at Woodjam are relatively low, but this is typical for porphry deposits in the area. Further expansion of resources will be necessary to make mining the deposit viable, but the project is well positioned in an area with several operating mines, which will help reduce start up costs. Solid gold grades, many over 1 g/t, from Vizsla’s drilling program may be just the thing to move the project over the line considering the ever-increasing price of the yellow metal.
Geology
The deposits form two distinct styles one is the classic alkalic Copper-Gold porphyry and the other is a more calc-alkaline style Copper-Molybdenum ore. Usually these deposits are found in widely separated geological environments however in this case they are only 4 kilometres apart. The Southeast Zone deposit (Calc-Alkalic) is hosted in a series of texturally variable quartz-monzonites (granite-type rock) while the Deerhorn (Alkalic) is hosted in sedimentary rocks intruded by monzonites. Each deposit has a distinctive alteration and metal signature with the Deerhorn hosting much more gold and having tourmaline breccias, while the Southeast Zone has distinctive extensive albitic alteration. Their proximity suggests a genetic linkage and perhaps an affinity with the High-K Cal-Alkalic (like Red Chris). However more study is needed to definitively pinpoint their relationships.
Further Reading
- del Real, I., Hart, C.J.R., Bouzari, F., Blackwell, J.L., Rainbow, A., Sherlock, R. and Skinner, T. (2013): Paragenesis and alteration of the Southeast Zone and Deerhorn porphyry deposits, Woodjam property, central British Columbia (parts of 093A); in Geoscience BC Summary of Activities 2012, Geoscience BC, Report 2013-1, p. 79–90. (PDF)
- Vizsla Copper: https://vizslacopper.com/projects/woodjam-project/overview/
