The original Red Cliff property is a former producing copper and gold property originally staked in 1908 located about 20 kilometers north of Stewart, British Columbia in the Skeena Mining Division. It consisted of 8 Crown Granted claims along Lydden Creek. The Crown Granted portion of the joint venture project is now owned 65% by Decade. The Company has identified 4 separate gold bearing zones called the Red Cliff, Upper Montrose, Lower Montrose and Waterpump within the Crown Granted claims.
The claim group extends from just west of American Creek with its confluence with Bear River along Lydden Creek for approximately 3 kilometers as well as for 5 kilometres along the west side of American Creek. The east side of the property is accessible by drill roads approximately 1.5 kilometers from paved highway 37A. It is underlain by lithologies of the middle Jurassic Hazelton Group. These rocks host significant precious and base metal deposits in the Stewart Camp including the Silbak Premier, Silver Coin, Sulphurets, Brucejack Lake, Big Missouri-Martha Ellen, Red Mountain and Eskay Creek deposits.
The Crown Granted portion of the property contains six different mineralization types identified in the exploration activities. Mineralization noted in the zones is as follows:
- Extremely fine grained pyrite in host rocks that have been pervasively altered to a mixture of sericite and quartz. Generally low gold values are associated with this mineralization.
- A stockwork of quartz veinlets carrying coarse-grained pyrite and chalcopyrite plus or minus visible gold. The Montrose zone contains this type of mineralization.
- A stockwork of fine pale yellow-brown sphalerite-galena with plus or minus chalcopyrite and plus or minus visible gold. The Montrose and Road zone contains this type of mineralization.
- Massive pyrite veins with variable amounts of chalcopyrite and quartz with generally low to significant gold values. The Montrose, Lower Montrose, Chimney and Red Cliff zones contains this type of mineralization.
- Massive hematite veinlets with coarse cube pyrite along wide stockwork zones. The Montrose and Lower Montrose contain this type of mineralization.
- Intensely silicified rocks, possibly intrusive with strong epidote and chlorite associated with quartz veins up to 5 metres wide, containing up to 25 % coarse pyrite and local minor chalcopyrite. This mineralization is located along the west side of the Montrose and Road zones.
Highlights from historical work for the three of the zones on the property include:
- The Red Cliff zone containing 2,385 m of underground development on 5 levels from 4 portals over a height of several hundred meters with limited Cu-Au production reported in 1910-12 and 1973. From 1910 – 12 production from the Redcliff zone amounted to approximately 1,136 tonnes estimated to average 5% Cu. In 1972 some 3,776 tonnes of ore was sent to a local mill. The only reserve estimate reported for the Redcliff Zone was in 1912 showing a total of 18, 900 tonnes averaging 3.19% Cu and 2.86 grams per tonne gold. This estimate was only for broken mineralized material within a stope on one of the levels in the mine. This estimate is historical and is not 43-101 compliant and is used for reference purposes only.
- The Lower Montrose zone occurs approximately 1000 meters to the north of the Red Cliff zones and consists of silicified andesite associated with shearing with pyrite, chalcopyrite, galena and sphalerite mineralization in quartz veins and stockworks. This zone has been developed along al short adit in a very steep part of the property. Initial sampling, conducted after discovery, above the portal area to one of the adits gave 198 g/tonne Au across 2.59 meters. During 1939-41 a total of 59 tonnes mined averaged 84.4 grams/tonne Au, 101 g/tonne Ag, 0.91% Cu, 3.5% Pb and 4.41 % Zn. In 1979 surface sampling gave 19.3 grams/tonne Au across 2.43 meters while 1987 surface sampling returned 7.93 grams/tonne Au across 3.81 meters. Recent drill intercepts include 9.3 grams/tonne Au across 1.71 meters.
- The Waterpump zone is a south extension of the Montrose zone with surface assay results in surface sampling returning 11.4 grams/tonne Au across 9.48 meters.
In the period from 2007 to 2018, a total of 74,020 meters of BTW and NQ size drilling in 409 holes on drill roads constructed during the various field seasons. Drilling was primarily conducted in the area of the Red Cliff zone and Montrose zones. The holes on the Red Cliff zone were drilled in order to test below and west of the underground working. Drilling extended the zone well below the lowest working as well as indicating that 4 separate zones of copper and copper–gold mineralization are present along a wide structure. Drilling on the Montrose zone was conducted in order to define the limits of mineralization within the zone.
The drilling to date for the Montrose zone at the Red Cliff property has allowed for a preliminary characterization of the mineralized system as follows:
- Mineralization consists of gold-bearing zones which are hosted by a 30 to 40 meter wide, near vertically-dipping shear zone which can be traced for over 2 kilometers, trending north-south, within the property;
- Gold-bearing mineralized zones, within the shear zone, have been intersected over a vertical distance of approximately 700 meters;
- Multiple gold-bearing mineralized zones have been identified within the wide shear zone;
- Gold is associated with abundant chalcopyrite and pyrite, most commonly in sulphide-bearing veins within the shear as well as gold-bearing stockwork zones outside of the vein systems;
- Gold is associated with fine galena-sphalerite veinlets along fractures peripheral to the chalcopyrite-pyrite stockworks;
- Gold is associated with sparse chalcopyrite, pyrite, hematite and epidote in quartz veins.
Property mineralization intersected to date indicates that the gold-bearing system is open along strike and to depth. The system has characteristics of a mesothermal, or deep-seated system, and as such can be expected to have significant depth continuity in addition to the along-strike continuity which is being shown by drill results. The width of the hosting structure, presence of high grades of gold, zones of stockwork mineralization peripheral to the vein-hosted gold and associated sulphides, and depth extent shown by drilling, indicate significant untested potential within this large system.
Metallurgical studies indicate gold recoveries of 94.8% and 97.6%, respectively for 2 separate composites of core samples from Red Cliff DDH-12-MON-61. Samples were from cut core and included the interval from 173.93 to 190.24 m (Red Cliff #1) and 200-208.99 m (Red Cliff #2). Within the intervals, gold is associated with sphalerite-galena stringers as well a separate pyrite-chalcopyrite stockwork. A summary of the work by SGS Minerals Ltd is quoted below:
“Gravity tests were conducted on the two composites by passing the ground pulp to a Knelson concentrator followed by Mozley table upgrading. The composites responded well to gravity concentration and 54.2% and 78.2% of gold on average were recovered into gravity concentrate at 447 g/t Au and 1618 g/t Au grade respectively for Red Cliff 1 and Red Cliff 2.
Batch cleaner flotation tests were performed on whole ore from the two composites to produce a Cu-Pb bulk concentrate and a zinc cleaner concentrate. The composites responded well to conventional flotation. For Red Cliff 1, the Cu/Pb bulk cleaner concentrate assayed 25.8% Cu, 7.86% Pb, 4.12% Zn and 323 g/t Au at recoveries of 88.1% copper, 79.2% lead and 81.7% gold. For Red Cliff 2, the concentrate assayed 25.7% Cu, 6.98% Pb, 3% Zn and 256 g/t Au at recoveries of 93.1% copper, 67.1% lead and 76.0% gold. The results were achieved from batch cleaner tests and the recoveries will be higher when locked cycle flotation tests are conducted. Optimization is needed to improve zinc flotation for both composites.
Pre-concentration and flotation tests were performed on the two composites and very good results were obtained. The copper grades were 25.2-25.4% at recoveries of 80.8-81.9%. The lead grades in the bulk cleaner concentrates were 6.95-8.58% at recoveries of 66.6-71.5%. The combined Pb recoveries (gravity + flotation) were 76% and 83.1% respectively for Red Cliff 1 and Red Cliff 2. Gold recoveries were high for the two composites and the total gold recoveries (gravity + Cu-Pb Conc) were 90.4% and 96.4% respectively for Red Cliff 1 and Red Cliff 2. The zinc rougher tailings were subjected to cyanidation and additional 4.4% and 1.2% of gold were leached out. The overall gold recoveries were 94.8% and 97.6%, respectively for Red Cliff 1 and Red Cliff 2.”
Select drill intersections in the drilling include the following:
|DDH No.||From||To||Core Length**||Gold g/t|
** True width is believed to be 70 % of intersection length.
|DDH No.||From||To||Core Length**||Gold g/t|
Due to the steep nature of the hillside, future work should include creation of underground drill stations to further explore the mineralized system.