The Sawmill zone is located near the eastern margin of the Stikine Terrane in south-central British Columbia, 5 kilometres south of Gibraltar East (093B 012). The Sawmill property lies about 6.4 kilometres south of the Gibraltar Mines concentrator, along the southern flank of Granite Mountain at approximately the 1067 metre elevation. Access is via a network of old logging roads which link the property to the paved road leading to Gibraltar Mines.
The dominant rock types in the region are metabasalt, limestone and argillaceous metasediments of the Mississippian to Triassic Cache Creek Group. These are intruded by the dioritic to quartz dioritic Granite Mountain Pluton and the (?)Cretaceous Sheridan Creek Pluton. The Granite Mountain Pluton has been affected by regional metamorphism (greenschist facies) and deformation along with the enclosing Cache Creek Group.
The mineralization consists of chalcopyrite, molybdenite and pyrite in quartz-carbonate veinlets parallel to foliation planes of the Granite Mountain diorite. Associated alteration is sericitic and chloritic and, in some cases, epidote alteration. Drilling also encountered mineralization within meta-andesite and an intrusive quartz porphyry. While chalcopyrite mineralization is fairly persistent, molybdenite distribution is more erratic. The Sawmill zone was outlined in 1979. As of December 31, 1992 geological resources were estimated at 68,492,450 tonnes of 0.244 per cent copper (CIM Special Volume 46, page 202).
The first claims of the Sawmill Group were staked in 1978 to cover a large I.P. anomaly and several older copper prospects. Of the prospects, the most important was the Iron Mountain property on which the first recorded work dates back to 1925. The chief focus of work for Gibraltar Mines was the I.P. anomaly which was located west of Iron Mountain over an area of very limited rock exposure. The anomaly had been outlined in 1978 and was attributed to a graphitic source rather than sulphide mineralization. Diamond drilling in 1979 by Gibraltar Mines however, revealed that extensive pyrite and chalcopyrite mineralization occurred within the I.P. zone, and by 1981, approximately 30 million tons of open pit inventory had been outlined, which graded at 0.28 per cent total copper and 0.022 per cent molybdenite. More diamond drilling and I.P. surveys followed from 1982 to 1986, but little change was made in the inventory. In 1986, from drillhole 86-22 between 91.4 and 154.5 metres, sampling resulted in values of 0.22 per cent copper and 0.13 per cent molybdenum sulphate (Assessment Report 15798). In 1990, a diamond drill program conducted within the Sawmill zone comprised four vertical NQ drillholes totalling 748.28 metres.
In 1999, Gibraltar Mines Ltd. conducted a program of geochemical surveys and soil drilling on the Green Group (MINFILE 093B 058) to determine if additional mineralized structures existed between the Gibraltar and Sawmill mineralized trends. No significant anomalous values were found (Assessment Report 26064). In 2000, an induced polarization geophysical survey was conducted on the entire property.
