The ACE developed prospect is hosted by the Upper Mississippian to Permian Nahlin ultramafic body, part of the Cache Creek Complex. The Nahlin body is 100 kilometres long and up to 8 kilometres wide and is the largest alpine-type ultramafic in the Canadian Cordillera. On the southwest it is faulted against Lower Jurassic sedimentary rocks (Inklin Formation, Laberge Group, and Upper Triassic Stuhini Group volcanic rocks) and on the northeast against Upper Paleozoic rocks of the Cache Creek Complex. This ultramafic body consists of oceanic crustal ultramafic rocks consisting of: peridotite, dunite, pyroxenite, which is in general serpentinized, and locally includes pods of nephrite jade and small bodies of listwanite, rodingite, and talc. The rocks weather uniformly reddish brown and are generally devoid of vegetation.
The asbestos fibre occurrence lies within pyroxenite which is slightly serpentinized and host phenocrysts of pyroxene. All of the ultramafic rocks are well jointed and are crosscut by acid to basic dikes. An extensive shear zone, about 305 metres long and 30 metres wide, has resulted in the rocks of the immediate area being serpentinized. There are three major shears in the area that branch off to the northwest which have also resulted in local serpentinization of the rocks.
The main fibre zone occurs on the north side of Camp Creek and consists of a continuous zone about 122 by 60 metres, containing greater than 5 per cent chrysotile with fibre lengths averaging about 2 centimetres. Another possible continuous fibre zone is located on the south side near the headwaters of Camp Creek. The chrysotile fibre occurs in two rock types. Firstly, as stockworks in the highly serpentinized zones and secondly, as lenses within the serpentinized peridotite which, in turn, are situated in peridotite with pyroxene phenocrysts. Disseminated magnetite occurs in the vicinity of the serpentinized zones and is associated with the chrysotile fibre veinlets.
In 1966, the Ace group of 15 recorded claims were held by Canadian Johns-Manville Company, Limited. Work on the property included geological mapping, and geophysical and geochemical surveys. In 1966, it was estimated from surface work that the fibre zone had a potential of up to 11,793,400 tonnes of ore (Assessment Reports 1030, 4913).
In 1973 Canadian Johns-Manville Co., Ltd. Established a grid over the old 1966 grid that was formerly used during a geological mapping program. The base line has a length of 2438 metres and offset lines were established at intervals of 122 metres. Readings were taken at 30-metre intervals along the offset lines. A northwest magnetic high was 4267 metres long and approximately 260 metres wide. A southwest magnetic high in an area of overburden was not closed but was reported to be much larger than the northern one. Fifteen kilometres of ground magnetic surveying was completed.
