The Nonda Creek developed barite prospect is situated on a southwest-facing mountain slope, 2.5 kilometres north of Nonda Creek and 14 kilometres east-northeast of the settlement of Muncho Lake on the Alaska Highway (Assessment Report 327, Map 2).
The region is characterized by moderate, north-northwest trending folds and northeast-verging thrust faults in Paleozoic sedimentary rocks belonging to Ancestral North America (Geological Survey of Canada Maps 1343A, 1713A). The area between Muncho Lake and Nonda Creek is composed of deformed Silurian and Devonian rocks in a series of west-dipping thrust sheets.
The Nonda Creek occurrence is in the Middle Devonian Dunedin Formation, on the eastern limb of an anticline in the hangingwall of a thrust. The formation is generally composed of grey, well bedded limestone, calcareous shale, and minor calcarenite and dolostone (Geological Survey of Canada Memoir 373). The Nonda Creek deposit, possibly of hydrothermal replacement origin, consists of a body or vein of barite which forms a white, resistant feature approximately 600 metres long, trending down the rubbly mountain slope. Its width is consistently 45 metres. It strikes north and dips very steeply east and is apparently discordant, possibly faulted, with respect to the adjacent, gently-dipping Dunedin limestone.
The deposit is not homogeneous nor mineralogically uniform. Some lenses within the body, 10 to 15 metres wide, are relatively pure, grading over 92 per cent barite (Assessment Report 327). Elsewhere the barite contains impurities of calcite and possibly witherite, but has the same white colour and so may be difficult to distinguish. Also, there are large lenses of mottled baritic argillite within the deposit.
The upper part of the deposit was analysed in order to estimate reserves. This zone was 120 metres long, 45 metres wide and 30 metres in depth; the last value is a conservative estimate as no drilling was done. Twenty-five samples were taken ranging from the pure baritic facies to marginal impure facies and country rock. Of importance is the high grade material which is generally between 95 and 98 per cent barium sulphate by weight (Assessment Report 327). After subtracting the volume of non- or weakly baritic rock, this upper body was estimated to contain 450,000 tonnes grading 92 per cent or more barite (Assessment Report 327).