The Cache occurrence is located at an elevation of approximately 1500 metres on an east-facing slope, approximately 2.5 kilometres northeast of the north end of Munro Lake.
The area is underlain by a dark, biotite-granodiorite of the Middle Jurassic Osprey Lake Batholith and granodiorite of the Lower Jurassic Pennask Batholith.
Mineralization appears to be structurally controlled, usually associated with steeply-dipping northeast-trending faults. Where mineralized, the granodiorite is altered to a greenish colour due to sericitization. At an upper exposure, near the historical adit, northeast-trending fractures dip north in a silicified granodiorite hosting tetrahedrite, pyrite, and chalcocite, the latter probably of secondary origin. Mineralization, which is locally strong, apparently persists for 6 metres northward to a fault that strikes north 80 degrees east and dips steeply to the north. A lower exposure, at 1340 metres elevation, consists of chalcopyrite, pyrite, and specular hematite as disseminations, seams and small masses. These occur mainly in the hangingwall of a fault that strikes north 46 degrees east and dips at 70 degrees northeastward. Sulphide mineralization is usually restricted to within a few feet of the fault. Minor quartz veining is also present. Further to the south and on strike of the lower zone, trenching on a northeast-trending fault exposed siderite veins with specular hematite, chalcopyrite, malachite and pyrite associated with zones of pyritic gossan and quartz stringers.
Work History
The earliest evidence of work on the property are two short adits, attributed to prospectors in the 1920s. Small shipments of wire silver were reportedly made at that time.
In 1966 and 1967, Koporok Mines Ltd. and Kerr Addison Mines Ltd. carried out a program of line cutting, road building, claim surveying, an induced polarization survey, trenching and blasting on the area as the Cache 1-40 claims. Sampling of a trench on the Cache 4 claim is reported to have yielded 0.90 per cent copper, 39.7 grams per tonne silver and 1.7 grams per tonne gold over 3.9 metres (Property File 823206). Also at this time, a 0.33-metre chip sample from a mineralized pod exposed in pit 1 yielded 1.93 per cent copper and 191.5 grams per tonne silver, whereas a grab sample of weakly mineralized granodiorite from a historical adit yielded 34.2 grams per tonne silver (Property File 825561).
In 1969, a 134.0 line-kilometre airborne magnetometer survey was flown over the claim area; several magnetic linears and disturbances were identified.
In 1986, Almaden Resources Corp. completed a program of prospecting, rock sampling and a ground electromagnetic survey on the area as the Rose claims.
This was followed in 1987 by 23 overburden drillholes; the concentrates from 15 of these were anomalous in silver and zinc. In 1988, 34 overburden holes, totalling 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 1989, Goldbrae Developments Ltd. completed a 160 line-kilometre airborne magnetic and electromagnetic survey on the area immediately east of the occurrence as the Deep property.
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.
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 (Rose-Munro [MINFILE 082ENW021]) that extends for at least 2.5 kilometres in an east-west direction.
In 2008, Almaden Minerals Ltd. completed a program of silt sampling on the area as the Munro Lake property.
In 2018, Almadex Minerals Ltd. completed a minor program of prospecting, geological mapping and rock sampling on the area as the Munro Lake East property.
