The Sowchea Creek vermiculite prospect occurs north of Sowchea Creek, about 17 kilometres southwest of Fort St. James.
Vermiculite is concentrated in a zone of weathered medium grained hornblende diorite of Jurassic age, exposed in 5 outcrops along a roadcut over a distance of 150 metres. Expandable mica also occurs in fresh medium grained diorite exposed southwest and northeast of the weathered diorite.
Exfoliation tests were carried out on a sample of vermiculite by CANMET, Energy, Mines and Resources Canada. Vermiculite content of the tested sample averaged 11.8 per cent (Geological Fieldwork 1990, p. 267, Table 3-1-1). The material may be too fine-grained for use as loose insulation; 89 per cent of the vermiculite was found to occur in size fractions below 1.65 millimetres. Bulk densities of the minus 1.65 millimetre size fractions, ranged from 357 to 434 kilograms per cubic metre, above the ASTM range of 88 to 128 kilograms per cubic metres specified for loose insulation.