The Sloko River occurrence is located about 2.9 kilometres east of the Sloko River approximately 59 kilometres south of the community of Atlin.

Parallel to the Sloko River is a major northwest-trending structure along which Mesozoic strata are in fault contact with Cache Creek Complex rocks. Immediately northeast of the Nahlin fault, upper Mississippian to Permian ultramafic rocks intrude the Cache Creek Complex and are in fault contact with younger Lower Jurassic Inklin Formation (Laberge Group) sediments to the southwest. The northern margin of the ultramafic exhibits both fault and intrusive contact relationships with Cache Creek Complex volcanics and sediments. The ultramafics are spatially related to the upper Mississippian to Permian Nakina Formation (Cache Creek Complex) and may be genetically related as well (Monger, Geological Survey of Canada Paper 74-47).

A zone of carbonatized serpentinite in the order of 100 metres wide is exposed for over 30 kilometres within the ultramafics along the trace of the Nahlin fault. The carbonatization is apparently limited to the vicinity of serpentinized shear zones within the ultramafics. Carbonate zones host numerous veins of quartz released in the conversion of serpentine to carbonate and are composed predominantly of fine grained ankeritic material which weathers to a buff colour.

Dolomite with minor magnesite forms coarsely crystalline vein carbonate. Magnesite with less than 5 per cent impurities occurs as very fine grained, pure white veins up to 1.2 metres wide in exposures of carbonatized serpentinite, particularly in the area northeast of the Sloko River.