The Rose-Munro Lake (Jass) occurrence is located approximately 500 metres south of Eneas Lakes Provincial Park and 24 kilometres northwest of the community of Summerland.
The area is underlain by granitic intrusive rocks of the Middle Jurassic Osprey Lake Batholith. To the north granodiorite of the Lower Jurassic Pennask Batholith is exposed.
The occurrence is hosted by a light-grey, weakly saussuritized porphyritic granodiorite, which has been intruded by Neogene dikes of quartz latite porphyry and quartz monzonite. Fracturing and cross-fracturing is common; one conspicuous fracture set has a strike between northeast and east with a steep southerly dip, and cross-fractures have various attitudes. Quartz and orthoclase form partly drusy veinlets up to 0.5-centimetre thick. Low-grade alteration is pervasive with local narrow envelopes of sericitized country rock enclosing mineralized fractures and quartz veins. Pyrite, molybdenite and chalcopyrite, all partly oxidized, are disseminated in and close to the veinlets. The molybdenite is fine-grained, more abundant than chalcopyrite, and primarily found in a later high-angle set of veins, which are almost always quartz-pyrite bearing.
Later work (1996) indicated the presence of two alteration assemblages in the occurrence area. The first style comprises sericite-chlorite alteration associated with early-stage quartz-pyrite±chalcopyrite±sphalerite±hematite veining, whereas the second style consists of potassic alteration comprising potassium feldspar, biotite, muscovite and anhydrite associated with late-stage quartz-potassium feldspar±molybdenite±hematite veining.
Work History
In 1966, Lakeland Base Metals Ltd. discovered the occurrence after following-up on anomalous stream geochemistry. Soil geochemical surveys, trenching and approximately 600 metres of percussion drilling were carried out in 1966 as a result of options by Brenmac Mines Ltd. and Brenda Mines Ltd. The results of the drilling are unknown, but the options on the property were dropped. In 1967, Lakeland attempted to extend geochemical anomalies by additional soil sampling but was unsuccessful.
In 1973, Canadian Occidental Petroleum Ltd. staked the area as the Mun property, and in 1974 they carried out an extensive program of rock, soil and stream geochemistry; magnetometer surveys and diamond drilling of three holes, totalling 275 metres. Several copper-molybdenum- zinc anomalies were outlined by the surface work and three were drilled. A drillhole (MUN74-3) is reported to have yielded 93.4 grams per tonne silver and 0.1 gram per tonne gold over 0.7 metre (Assessment Report 25298). This drillhole was located approximately 1.7 kilometres southeast of the main occurrence. Widespread but weak molybdenite and chalcopyrite mineralization was traced on surface over a northeast-trending distance of approximately 740 metres and a width of 240 metres.
In 1976, a Regional Geochemical Survey release identified highly anomalous silver values in streams draining the Munro Lake Plateau. As a consequence, in 1977, Canadian Occidental shifted their focus to the silver potential of the property, reanalyzed their soil and drillcore samples for silver and drilled a 171-metre BQ diamond drill hole. The best intersection, between 99.0 and 100.6 metres, assayed 0.396 per cent zinc and 10 grams per tonne silver over 1.6 metres (Assessment Report 6558).
In 1980, Cominco Ltd. completed a program of geological mapping and soil sampling on the area as the Glen claims.
In 1981, Canadian Occidental trenched the area north of the 1977 drillhole. The northernmost of the two trenches exposed a highly altered, rubbly, friable granodiorite with anomalous mineralization. A 108.2-metre section averaged 3.06 grams per tonne silver, 0.15 per cent zinc, 0.05 per cent copper, 0.003 per cent molybdenum and 0.008 per cent lead (Assessment Report 10445). This was considered subeconomic and no further work was recommended.
In 1986, Almaden Resources Corp. staked the area and proceeded to carry out a very low frequency electromagnetic survey. The survey successfully identified two conductors of significant strike length, as well as multiple ‘one-line’ anomalies. This was followed in 1987 by 23 overburden drillholes; the concentrates from 15 of these were anomalous in silver and zinc and hole 13 yielded up to 1.172 per cent zinc and 150 grams per tonne silver (Property File 000933). In 1988, 34 overburden holes totaling 296 metres were drilled. Analysis by heavy mineral concentration identified three subparallel east-northeast trending gold-silver-zinc anomalous zones in the basal till layer.
In 1990, Almaden carried out a geophysical program consisting of line-cutting and magnetometer, very low frequency electromagneticand scintillometer surveys. The program outlined a number of east-northeast–trending anomalous areas believed to be associated with a lineament that is known to host quartz veins containing gold and silver values.
In 1994, Almaden contracted Delta Geoscience Ltd. to carry out induced polarization and resistivity surveys of the property. The results suggested that a large pyritic alteration system had been identified, measuring approximately 900 metres wide by 1600 metres long in an east-west direction. Sulphide mineralization within the main induced polarization anomaly appears to be strongly controlled by intersecting northeast and east-west structures (George Cross Newsletter No. 220, 1994).
During 1996 and 1997, two drilling programs were conducted to test the eastern and western portions of a large 4-kilometre-long induced polarization chargeability anomaly. The drilling programs partially defined a large, low-grade porphyry silver-copper-molybdenum anomaly that extends for at least 2.5 kilometres in an east-west direction. The strongest alteration and mineralization to date was intersected in drillhole M-96-3 and yielded 5.54 grams per tonne silver, 0.047 per cent copper and 0.020 per cent molybdenum over 231.9 metres (Assessment Report 25298).
No work was conducted on the area again until 2008, when Almaden Minerals designed a stream sediment sampling program to define areas of greater metal concentration within the geophysical anomaly. The sample results included copper (greater than 112 parts per million), molybdenum (greater than 22.7 parts per million) and silver (greater than 5 parts per million) concentrations, defining a roughly 4- by 2-kilometre area of elevated stream sediment values for these elements (Assessment Report 30279).
In 2013, Green Swan Capitol Corp. completed a 222.7 line-kilometre airborne magnetic and electromagnetic survey on the area as the Mikayla property.
In 2018, Almadex Minerals Ltd. completed a minor program of prospecting, geological mapping and rock sampling on the area immediately east of the occurrence as the Munro Lake East property. Also, in 2018 and 2019, CBLT Inc. completed a program of soil sampling and airborne geophysical interpretation on the Mikayla property.
