The Moss occurrence is located between Chuchi and Witch lakes about 80 kilometres north of Fort St. James.
The Moss showing is hosted within the Upper Triassic Witch Lake Formation of the Takla Group. On the Chu claims, these rocks are intruded by coeval Takla Group equivalents consisting of crowded plagioclase hornblende porphyry monzonites and monzonite intrusive breccias.
The showing occurs in an area of strong alteration and mineralization related to a larger porphyry system between Chuchi and Witch lakes, the Chuchi-Witch alteration halo (Fieldwork 1991, pages 114-115) (refer also to the Witch occurrence, 093N 164). Surface weathering has produced a well-developed limonite and goethite cap over the occurrence, ranging in thickness from less than 1 metre up to 3 metres. Rocks exposed within trenches are variably altered augite (plus/minus plagioclase) porphyritic andesites intruded by a series of monzonite dikes. Alteration consists of a propylitic assemblage consisting of epidote, sericite, carbonate, chlorite plus/minus albite; and a skarn assemblage consisting of garnet, actinolite, clinozoisite, wollastonite, sphene and diopside. Secondary biotite and weak potassium feldspar alteration is minor and occurs locally. In stronger zones of alteration, the original textures of the rock are destroyed.
Mineralization consists primarily of disseminated pyrite, pyrrhotite, magnetite and localized chalcopyrite. Minor occurrences of marcasite, galena and bornite have been seen in thin section. The strongest zones of mineralization contain 10 to 15 per cent pyrrhotite as blebby aggregates with the other sulphides. Gold mineralization is reported to be associated with stronger zones of alteration and in particular, zones of better-developed skarn.
Trench sampling has outlined a zone grading 1.6 grams per tonne gold and 0.012 per cent copper over 56 metres east-west in Trench I, and 1.1 grams per tonne gold and 0.016 per cent copper over 34 metres north-south in Trench II (Assessment Report 21988, page 11). Nine diamond-drill holes were drilled in 1991 in and around the Moss prospect. The best intersection obtained was 0.064 gram per tonne (64 parts per billion) gold and 0.035 per cent (347 parts per million) copper (Assessment Report 21988, page 17). Drilling beneath and adjacent to the mineralized trenches encountered only anomalous gold and copper grades.
Intermittent exploration work has been performed in the Witch property area since 1971. This work has focused on the search for porphyry copper occurrences. In 1972, Attila Resources Ltd. performed geological mapping and collected 996 soils samples and conducted 24.6 kilometres of ground magnetic surveying on its DP property on the northern part of that area that later became the Witch property (Chu 1-10 claims) in the late 1980s and early 1990s (Assessment Report 3468).
Sahqua Minerals Ltd. did geochemical soil sampling, magnetic surveying, induced polarization (IP) surveying and diamond drilling from 1979 to 1980. Only the IP survey appears to be documented (Assessment Report 7887). This survey, on the Bag 1 claim of Sahqua Minerals covers part of the Composite Stock anomaly drilled in 1995.
The Chu 1 to 10 mineral claims were staked in 1988 by Westmin Resources Limited to cover an airborne magnetic anomaly associated with indications of a porphyry copper occurrence. Rio Algom Exploration Inc. optioned the Witch property from Westmin Resources Limited in 1989. Their work included airborne magnetic surveying followed by line cutting, soil sampling, geological mapping and IP surveying. The Moss Showing was discovered as a result of this work. In 1990, Rio Algom continued soil sampling, geological mapping, prospecting, rock sampling, trenching, line cutting and IP surveying. Two trenches at the Moss Showing area assayed 4.7 grams per tonne gold and 0.10 per cent copper across 7 metres, and 3.8 grams per tonne gold with 0.10 per cent copper across 4 metres (Assessment Report 20899). In 1991, Rio Algom Exploration Inc. completed 644 metres of trenching and 1327 metres of diamond drilling in nine holes at the Moss showing area. Results were disappointing with 64 parts per billion gold and 347 parts per million copper over 52 metres in one of the holes directly below the mineralized trenches (Assessment Report 21988).
In 1994, Westmin Resources Limited completed grid surveying, soil sampling, lithogeochemical sampling and geological mapping in the Chu 9 portion of the Witch property. This work completed preliminary geochemical and geological coverage of the property; 859 soils and 50 rocks were analyzed. In June 1995, Artina Resources Ltd. and Westmin Resources Limited completed 31.2 line-kilometres of IP surveying at the Chu 9 mineral claim area. This work completed geophysical coverage of the property. Chargeability anomalies occur along both the north and south margins of the magnetic high associated with the Arm Anomaly, a geochemical anomaly with associated magnetic high that extends over 4 to 5 kilometres in and east-west direction south of the Moss showing area.
In November 1995, Artina and Westmin completed 301.15 metres of diamond drilling in three holes at the Witch property. This work tested the southern part of the Composite Stock Anomaly. Refer to the Witch occurrence (093N 164) for further details of work done on the Witch property.
In 2010, Equity Exploration Consultants Ltd. completed an exploration program on the area containing the occurrence. Significant results included soil samples grading 2.67 grams per tonne gold and 0.549 per cent copper (Assessment Report 31674).
