Great Northern Zone

The Great Northern prospect is located between 1550 and 1850 metres elevation on the east side of Great Northern Mountain, about 3.2 km northwest of Ferguson. The Great Northern claim (L.1099), is one of several crown-granted mineral claims that straddle the border between NTS Map sheets 82K/11 and 82K/12. The tenures cover the Great Northern [082KNW061], True Fissure [082KNW030], Broadview [082KNW031], Blue Bell [082KNW060] and St. Elmo [082KNW062] deposits. The Great Northern property is southeast of the True Fissure and probably covers the same vein. Some of the True Fissure workings extend onto the Great Northern crown granted mineral claim.

Some of the cherty exhalite and massive pyrite found on the surface dumps, Great Northern Zone

Click on the following links: Great Northern 1 and Great Northern 2 to see typical pictures of the gold-bearing massive sulfide ore found at surface).

The first showing in the area was found on the Great Northern claim in 1890. Other discoveries soon followed, and the entire vein system was located before the turn of the century. Small-scale exploration and development was carried on by the locators, or bondholders, for a number of years. The Great Northern claim was bonded to a Montana company in 1896 and an adit was driven the following year and at least one bulk sample was shipped to the smelter. According to Gunning (GSC MEM 161), 33.5 tonnes worth "$47 per ton" were shipped; however, only 15 tonnes are recorded. The Great Northern (L.1099), Hillside (L.1098), and Great Western Fr. (L.1102) were crown-granted to Hugh McPherson and Associates in 1898. After a period of closure, the adit was reopened in 1906 and more work was done on the claim in 1913, 1917, and between 1928 and 1930. In 1928, there were four adits on the property but the upper three, which were short, had already caved. The lower adit, No. 4, was still open for 103 metres and exposed the vein for approximately 75 metres. The more recent work has been confined to No. 4 adit. In the 1950s, the Great Northern Group was owned by the D. McPherson Estate. By 1958, all of the workings had collapsed. In recent times, the Great Northern has been included with the True Fissure, Blue Bell, St. Elmo and Broadview in a single property. In 1987, the ground was owned by Sibola Mines Limited.

The True Fissure and related occurrences are in grits and phyllites of the middle division of the Broadview Formation in the core of a major anticline that is believed to be a large drag feature on the southwest limb of the main Silver Cup Anticline. The mine area is on the southwest side of the Cup Creek Fault, near the axis of the drag fold anticline, which strikes and plunges to the northwest. The area has been subdivided into four structural blocks by later faults. It is cut by the Great Northern Fault, which is a sinuous, northerly striking and relatively shallow easterly dipping reverse fault that separates the mine geology into eastern and western blocks. Both side of the fault are disrupted by movement on the Broadview Fault, a younger, northeast trending structure. Most of the mineralization is in graphitic schists in the footwall of the Great Northern Fault. The geology of the mine area is described by Fyles and Eastwood (EMPR BULL 45). The Great Northern Fault is a gouge and breccia zone of variable width that has been more or less injected with quartz and carbonate and a lens-shaped vein of quartz and carbonate follows the footwall of the fault for 365 metres from Fissure Creek to the True Fissure No. 1 adit, and may continue south to the Great Northern mine workings. The hanging wall of the vein is sharp but the footwall is locally highly diffuse. The vein is defined as having in excess of 50 percent quartz and carbonate. In some places it splits into several strands that are separated by quartz vein stringers in crushed country rock. The vein consists of massive, crushed, quartz and coarse-grained, buff colored, ankerite and siderite. In the True Fissure mine, the "vein" may average approximately 10 metres in width but the siliceous upper portion is commonly only half of that. Vugs lined with quartz crystals occur but are not common. The sulphide minerals are pyrite, sphalerite, galena, chalcopyrite, argentiferous tetrahedrite and possibly bournonite. They appear to have been introduced after the gangue.

In 1928, the Great Northern vein was described by Starr (EMPR PF: Starr Report, 1928) as being similar to the True Fissure [082KNW030] occurrence, which is in graphic schist a short distance to the northwest. The width of the vein in the No. 4 adit was uncertain, but greater than the drift. It had a strike of 145 degrees and a dip of 35 degrees to the northeast. It was composed of varying amounts of quartz and lesser carbonate, in stringers, considerable bodies replacing slates, and between beds of partially silicified slate. The vein contains pyrite, galena, sphalerite and minor chalcopyrite with a little gold and good silver values. The mineralization is erratically distributed within the vein but locally produces significant, if small, concentrations. The No. 1 adit was a short crosscut through the vein and there was some quartz and ore-sulphide on the dump. Some sacks of shipping ore may have been removed. The No. 2 adit was also a crosscut to the vein, although it also drifted along it for a few metres. A small concentration of high-grade sulphide was reportedly found at the intersection of the main vein with a small cross vein but the dump suggests that most of the vein was low in grade. The No. 3 adit is also supposed to have crosscut the vein, but there is little quartz to show for it. The No. 4 adit encounters and follows the vein and has a short crosscut on "good looking" ore. The zone is 1.37 metres wide and assays 2.74 grams per tonne gold, 970 grams per tonne silver, 10.6 per cent lead, 5.7 per cent zinc and 1.25 per cent copper. It is approximately 3.0 metres in strike length, but its depth extent is uncertain.

Three grab samples collected by Sibola Mines Limited along the surface trace of the vein, over 24.38 metres of strike length, returned the following values (1) 6.86 grams per tonne gold, 2839 grams per tonne silver, 28.3 per cent lead and 2.50 per cent zinc; (2) 5.48 grams per tonne gold, 1762 grams per tonne silver, 28.5 per cent lead and 4.56 per cent zinc; and (3) 3.77 grams per tonne gold, 1447 grams per tonne silver, 15.0 per cent lead and 0.75 per cent zinc (PR REL: Stockwatch December 15, 1987).

Great Northern Zone

  • The Great Northern Zone if found directly south of the True Fissure Mine, and was worked in the late 1800's and early 1900's.
  • The Great Northern Zone is both base and precious metal-rich, and continues at depth well below the current drilling levels.