The Croesus (CR) or South Porphyry occurrence is located 2.8 kilometres west-northwest of the summit of Mount Morice about 17.5 kilometres south-southwest of the community of Houston.
The South Porphyry area is underlain by Lower Jurassic Telkwa Formation (Hazelton Group) volcanic rocks which have been intruded by plugs of Eocene Nanika Plutonic Suite and the Late Cretaceous Bulkley Plutonic Suite. The Telkwa Formation is composed primarily of breccia, tuff and flows of andesitic to rhyolitic composition while the intrusions are composed of granodiorite, quartz monzonite and felsite which are in part porphyritic.
A strong zone of copper-molybdenum mineralization occurs at the South Porphyry zone associated with a felsic quartz porphyry and quartz feldspar porphyry (QFP). The quartz porphyry is highly silicified and locally cut by thin quartz veinlets containing pyrite-molybdenite-chalcopyrite. The four main styles of mineralization observed at are: chalcopyrite in silicified andesite, disseminated and veinlet mineralization in QFP, micro-veinlet and veinlet mineralization in felsic intrusive rocks, and localized molybdenite-rich stockworks. Chalcopyrite and molybdenite are the primary minerals of economic importance with silver being present as an accessory.
A 2007 drillhole in felsic porphyry intercepted 83 metres of mineralization assaying 0.347 per cent copper, 0.025 per cent molybdenum and 1.68 grams per tonne silver (Assessment Report 30072). As of the 2007 drilling, the mineralized porphyry has been outlined in drill core to a size approximately 975 metres in length and 110 to 180 metres in width. The mineralization remains open to the west.
The earliest recorded work on the property consists of prospecting and trenching by J. Van der Wijk prior to 1963. In 1963 and 1965, Amax Exploration Inc. examined the property and subsequently optioned the property from March 1966 to February 1967. Amax completed a program of geologic mapping, geochemical and geophysical surveys (induced polarization), 183 metres of bulldozer trenching, and 985 metres of diamond drilling on the South Porphyry. Note: In 2007, Manson Creek Resources indicated that the Amax drilling on the Van occurrence (093L 269) was on the same zone that they referred to as the South Porphyry (093L 006).
The property was optioned by Bovan Mines between September and December 1967. Bovan Mines drilled five core holes on the South Porphyry zone. In 1970, Van der Wijk and A. Salo discovered areas containing chalcopyrite within volcanic rocks, and in July 1970 the property was optioned to Falconbridge Nickel Mines Ltd. The property includes part of an area on the west side of Morice Mountain investigated by Amax Exploration Inc. in 1966. Much of the activity centred on two chalcopyrite showings located to the north and northeast of a small quartz porphyry stock and the old Amax camp site. Falconbridge conducted geologic mapping, 262 metres of trenching, soil and rock geochemical sampling, and geophysical (EM and magnetometer) surveys. Falconbridge described the Upper and Lower showings (Geology, Exploration and Mining in British Columbia 1970).
It appears the "Upper" and "Lower" showing were defined by Falconbridge about 1970 (Geology, Exploration and Mining in British Columbia 1970). There is little documentation that clearly confirms their location. Previous researchers deduced that Sholto (093L 202) was the Upper showing and that Success (093L 007) was the Lower showing. However, Assessment Report 10563 plots them on their Mound claims and provides further clues on their given maps. Comparing the Mound claim location map to the Mound Geology Maps 1 and 2 may help future explorationists corroborate their findings. Map 1 and 2 do contain Mound claim post plots.
In 1977, Cities Service Minerals Corp. conducted an induced polarization (IP) survey, a geochemical survey, geologic mapping and drilled 431 metres of core in five holes. In 1977, the area of interest on the Rain claims by Cities Services Minerals Corporation was focused on a "north breccia zone" consisting of angular fragments of lithic tuff healed by quartz-pyrite-chalcopyrite. Two preliminary IP traverses conducted in the late summer of 1976 over the exposed breccia revealed that it was weakly polarizable and had a high apparent resistivity. As a result, a more comprehensive IP survey was undertaken in 1977 to define the limits of the breccia. The survey showed a weak IP anomaly centred across the Rain 1 and Rain 2 boundary with potential drillhole locations given (Figure 6, Assessment Report 6311). The 1977 Rain area work plots in the South Porphyry prospect area delineated by Manson Creek Resources in the mid- to late-2000s has been merged under MINFILE number 093L 006.
The Rain claim covered some of the southern portion of the 1982 Mound property claims but seemed to cover roughly the same ground as the CR claims of Manson Creek in 2008 which covered the North Porphyry showing and the South Porphyry prospect. Pertinent reports do not provide enough information on the 1977 work done.
In 1981, Churchill Energy Inc. conducted geologic mapping over the northern part of the district. Between 1985 and 1987, J. W. Moll staked the area and collected and analyzed 321 soil samples. In 1982, Churchill Energy Inc. held the Mound 1 to 11, which as shown by their report maps contain an Upper and Lower showings (Maps 1 and 2, Assessment Report 10566). The Mound claims would have covered the North Porphyry (093L 006) showing as it was defined later by Manson Creek Resources on their CR property. The Sholto (093L 202) was thought to be the Upper showing previously reported by Falconbridge and Success (093L 007), the Lower showing.
In 1993, Cominco Ltd. conducted limited geologic mapping and an IP survey. In 1994, J.W. Moll staked the CR claim area and has subsequently drilled and followed up with several shallow holes over the next few years. In 1998, Moll drilled two X-ray holes on his CR property totalling 48.2 metres. In 1999, Moll drilled 2 X-ray holes on his CR property totalling 55.5 metres. In 2001, Moll drilled two exploration holes on his CR property, totalling 50.9 metres. In 2002, John Moll drilled one X-ray hole (CRO2-01) 38.1 metres to follow up previous work. Pyrite and chalcopyrite mineralization were observed in several veinlets throughout the hole. The 3.8-metre interval from 25.3 to 29.1 metres averaged 0.17 per cent copper (Assessment Report 27205).
Manson Creek Resources Ltd optioned the property in June, 2004 and carried out a field exploration program on the property consisting of geologic mapping, line cutting, backhoe trenching, rock and soil sampling, and a ground magnetometer survey. A total of 15.2 line kilometres of grid were cut on two separate grids. One grid extends over the North Porphyry zone (8.9 line kilometres) while the other grid covered the South Porphyry zone (6.3 line kilometres). Over the course of the program, 172 rock samples were collected as were 512 soil samples on the two grids. Trenching on both the north and south grids totalled 412 metres in six separate trenches and 15.2 line kilometres of magnetic surveying was completed.
Manson Creek embarked on a two phase exploration program on the CR Property in 2005. In June, a crew completed 4.0 line kilometres of soil sampling on infill lines between the 2004 cut grid lines over the Burn anomaly. The 143 soil samples provided further refinement as to the extent of the significant copper in soils anomaly.
An 8-hole, 1580 metre diamond drill program followed the receipt and interpretation of the geochemical survey. The drill program was designed to test for the source of the Burn geochemical anomaly as well as to provide further information on the mapped South Porphyry at depth. Three drillholes tested for the source of the Burn anomaly and all intersected previously unknown mineralized porphyry. This drill program extended the known strike length of the porphyry to 975 metres, though it remained open to the west and to depth.
In 2005, the discovery of additional porphyry was made in an area of sparse outcrop and abundant cover. In 2006, Manson Creek completed a 4.0 line kilometre IP survey over the western extent of the porphyry and areas beyond to the west in an attempt to define additional porphyry. In 2007, a 7-hole, 1987 metre diamond drill program was completed in order to determine the depth of the intrusion and to test the western extent of the porphyry outlined by the 2006 IP survey. Three of the holes successfully intersected mineralized porphyry near surface and at depth. The two westernmost holes failed to intercept mineralized porphyry. Newly discovered north trending normal faults, however, may have displaced the mineralized porphyry to greater depths westwards. The near surface, westernmost extent of the intrusion has been delineated, but it remains open at depth. The 2007 drilling outlined the strongly mineralized potential of the South Porphyry. The South Porphyry was tested with drillholes 07CR-14 and 07CR-15 with significant mineralized intercepts both at surface and at depth, with drillhole 07CR-15 ending in high molybdenum values.
In 2011 and 2012, Quartz Mountain Resources Ltd. held the considerable Buck and Karma property. In 2011, the company conducted 3906 kilometres of aeromagnetic surveying which covered many occurrences in the region including the Peacock (Assessment Reports 33176, 34048).
Refer also to the North Porphyry occurrence (093L 343), located about 1.4 kilometres to the north.
