The Black Bluff occurrence is located on a southwest facing ridge side above Snippaker Creek, approximately 9 kilometres upstream of its confluence with Iskut River. The prospect is approximately 92 kilometres northwest of Stewart, in northwestern British Columbia.
The area of the Black Bluff prospect is underlain by a sequence of intermediate volcanic and related sedimentary rocks of the Upper Triassic Stuhini Group, cut in at least two places by a large igneous intrusion. Strata are bracketed and transected by several north-northeast, east-northeast and southeast trending regional structures, some of which have undergone recent movement, while others are of Jurassic age. Volcanic rocks include breccias with limestone clasts and minor felsic volcanic members. An identifiable Permian crinoidal limestone marker unit occurs in the faulted and folded sedimentary rocks. The limestone unit is interbedded with fragmental lapilli tuff to tuff breccia of coarse augite phyric basalt; accordingly, the volcanic rocks are assigned to the lowermost Triassic period. Dispositions of mapped sedimentary and intrusive rocks on the property suggest that the former occurs as roof pendants in the Lehto Batholith. The batholith is related to the Early Jurassic Texas Creek Plutonic Suite. It is hornblende plus plagioclase phyric and K-feldspar megacrystic. The batholith rocks in the area are cut by near-vertical northeast trending dykes of biotite phyric, fine grained leucocratic material.
The Black Bluff showing is a zone of intense K-feldspar alteration which has destroyed all but the largest K-feldspar and amphibole megacrysts in the host intrusion. The megacrysts have been replaced by epidote. Based upon their morphology, the host is part of the Lehto polyphase intrusion. The K-feldspar alteration is cut by multiple generations of veins, such that, in places, even the alteration assemblage has been replaced entirely to form a quartz plus magnetite stockwork with patchy sulphide mineralization. The latter is developed along pre-existing fractures or disseminated in both the quartz stockwork and host alteration. At least four generations of veins were identified: an oldest, banded quartz plus magnetite vein set, a planar quartz plus magnetite set, possibly conjugate; a planar quartz plus or minus magnetite set, with patchy alteration of magnetite to sulphide minerals (associated with epidote); and (latest) a quartz plus or minus sulphide plus or minus stockwork and/or discrete quartz plus sericite plus pyrite veins.
While the area of the Black Bluff showing area was explored in previous years, it was in 2002 that this mineralized zone was discovered. Mineralization is considered typical of localized high-grade skarn mineralization and more widespread lower grade gold-copper mineralization typical of alkaline porphyry systems.
Three drillholes were completed on the Black Bluff showing in 2002 by Parkside 2000 Resources Corporation and Goldrea Resource Corp., and 6 more holes were completed on gold and copper in soil anomalies about 400 metres north and northwest. The drill holes yielded poor results from the Black Bluff alteration zone but the holes to the north yielded up to 1.6 grams per tonne gold and 0.18 per cent copper over an interval of 1.3 metres; another hole yielded 0.3 gram per tonne gold and 0.55 per cent copper over 15.2 metres (Assessment Report 27193). Also in 2002, 7.1 kilometres of Induced Polarization surveying and 12.2 kilometres of ground magnetometer surveying were completed.
Work History
The specific exploration history of the ground covered by the BX 1-4 claims was described in Assessment Report 24437 and is reported in full in Shan (104B 023).
Exploration on the CAM 1-4 claims (Assessment Report 17129 (Todoruk and Ikona, 1987) and Assessment Report, 19760 (Goad, 1989)) addressed ground now covered in part by the BX 9 claim. The primary focus was exploration of the Chilli showing (recorded in MINFILE as the CAM4/Enterprise showing (104B 364)). Following an unfavourable report (Assessment Report 20371(Kuran 1990)), the claim was returned to the vendor and subsequently lapsed.
The BX 10 claim mainly covers ground originally staked as the Mystery claim group (Assessment Report 18198 (Scroggins and Ikona, 1988) and Assessment Report 20126 (Todoruk and Ikona, 1989)) and the Arc 10-12 claims (Assessment Report 21067 (Grill et al., 1990)). The property underwent an airborne geophysical survey, prospecting and soil and stream sediment surveys (Assessment Report 20845 (Grill and Wong, 1990)) followed by limited diamond drilling (Assessment Report 22036 (Grill and Savell, 1992)), after which the property was returned to the vendor. Exploration in this area extended well below tree line and was rewarded by the discovery of zones with significant strike length.
Work completed at Black Bluff in 2014 and 2015 by Colorado Resources Ltd. included limited soil sampling, prospecting, and chip sampling. Sample 2637220, a float sample of quartz-breccia assayed at 35.5 grams per tonne silver, 0.422 per cent copper, 5.44 per cent lead, and 4.14 per cent zinc (Assessment Report 35943).
In 2016, Colorado Resources field crews collected 73 rock and 337 soil samples at Black Bluff. Soil and rock sampling at Black Bluff outlined a copper, molybdenum, lead and zinc zoned geochemical anomaly. Sampling could not be extended further east due to ice cover. The copper-rich core of the anomaly, containing mainly greater than 4,877 parts per million Cu soil samples covers fine grained clastic sediments and diorite to quartz diorite dikes cutting the main Lehto batholith. The Cu-rich core extends for about 1,000 metres north-northwest and is up to 400 metres wide. The copper anomaly is flanked by highly elevated molybdenum to the south and west and by elevated lead and zinc (Assessment Report 36761).
In 2017 crews collected 38 rock sample and 155 soil samples. Soil Sampling covered an approximate area 1,200 by 500 metres northeast and southeast of the Black Bluff occurrence. There is a prominent copper, silver and zinc soil anomaly with erratic elevated gold assays in the northern section of the soil sampling (Assessment Report 37604).
