The Sky occurrence is located approximately 3 kilometres east of Vines Lake and 90 kilometres north of the community of Dease Lake.
The area is underlain by an intraformational sedimentary breccia intruded by two subvolcanic diorite porphyry sills. The breccia is underlain by Upper Paleozoic Sylvester Allochthon (Mississippian Slide Mountain Complex) greenstones.
The Sky vein system occurs along an east-trending fault that dips 75 degrees north. The veins average 4.0 metres in width and have a strike length of at least 650 metres. A listwanite (quartz-carbonate) alteration zone flanks the north contact. The vein hangingwall is well-mineralized, with tetrahedrite, sphalerite, pyrite, chalcopyrite, malachite and azurite. A quartz to quartz-carbonate stockwork cuts the vein and extends 5 to 10 metres into adjacent Upper Triassic Slide Mountain Complex argillites. These stringers contain only traces of pyrite. Northeast-trending faults cut the main vein in at least six places.
Gold values as high as 35.83 grams per tonne over 2.3 metres have been reported but assays have been erratic (Assessment Report 11074).
In 1982, diamond drilling yielded up to 17.7 grams per tonne gold and 45.6 grams per tonne silver over a 1.5 metre section of listwanite hosting quartz veins with tetrahedrite and fine native gold in hole MBC82-15 and 4.0 grams per tonne gold over 1.3 metres of listwanite with barren looking quartz veins in hole MBC82-15A (Assessment Report 11074).
Drill hole TM09-011 is reported to have intercepted a 50-metre interval of low-grade mineralization in the upper portion of the drillhole with assays of up to 1.95 grams per tonne gold over an unknown length (Assessment Report 31396).
Diamond drilling in 2012 targeted the structure too shallow so holes TM12-01 through TM12-03 only intersected insignificant quartz veins hosted in sedimentary rock of the hangingwall sequence. Given that listwanite crops out at surface with sedimentary rocks on both hangingwall and footwall sides, it was speculated that the Table Mountain Thrust is very shallow. These first few drillholes, however, demonstrate that the sedimentary sequence is thicker than suspected and that the listwanite exposures demarcate the steep Sky vein structure, not the thrust. The listwanite occurs well above the thrust and it is unclear if this is common near other Table Mountain veins. Later holes were stepped back and intersected very thick quartz veins ranging from 10 to 24 metres (true width) at greater depths. Unfortunately, no highly auriferous sections of the Sky vein were intersected, consistent with quartz-carbonate-pyrite–only vein intercepts. No visible gold was observed in the drillcore and only very rare base metal sulphides were identified. The best intercept from the 2012 drilling is 3.25 grams per tonne gold over 1.86 metres (Assessment Report 33710).
Work History
The area has been explored in conjunction with the nearby Table Mountain (MINFILE 104P 070) mine and a completed exploration history of the area can be found there.
In 1979, Erickson Gold Mining Corporation optioned the McDame property, including the area of the Sky vein, to Esso Resources Canada Limited. The next year, Esso conducted the earliest systematic exploration work on the Sky vein area including geophysics, mapping and geochemical surveys. The Sky vein was discovered in 1980 through prospecting along the sedimentary rock/basalt contact (i.e., the Table Mountain thrust). That year, several soil and rock samples were collected from the Sky vein area and 23.87 kilometres of lines were cut and picketed. In 1981, fieldwork included geological mapping, trenching and diamond drilling. A bulldozer was used to strip 400 metres of the Sky vein, which provided good exposure for detailed mapping. In 1982, an exploration program by Esso Resources Canada Limited included geological mapping, a soil survey (96 samples), diamond drilling (2 holes totalling 204.3 metres) and resampling of trenches along the Erickson Gold Mine switchback. During 1982 to 1983 14 drillholes, totalling 1223 metres, were completed but produced mixed results. Drilling was not successful in extending the known Sky vein and associated listwanite body to the west. No further work was recommended on the Sky vein following this drill program. In 1986, the property was returned to Erickson who drilled four holes, totalling 964 metres, on the Sky vein.
In 1995, Cusac Industries Ltd. completed five drillholes at the Sky vein; however, no report was filed for assessment.
During 2008 through 2012, Hawthorne Gold Corp., later China Minerals Mining Corp., completed regional programs of geological mapping, geochemical (rock and soil) sampling and 11,657 line-kilometres of airborne magnetic, radiometric and electromagnetic surveys on the area as the Cassiar Gold property. In 2009, Hawthorne drilled one hole west of the Sky vein that did not return significant results. In 2012, China Minerals Mining Corporation completed a drilling program of 10 holes, totalling 1355.4 metres, on the Sky vein prospect.
In 2019, Margaux Resources completed a program of prospecting, geological mapping and rock sampling on the area as the Cassiar Gold property.
In 2020, Cassiar Gold Corp. completed a program of regional photogeological interpretation, prospecting and rock sampling on the Cassiar Gold property.
