The J occurrence is located about 5 kilometres south of Letain Lake.

A band of serpentinized peridotite occurs at the thrust fault contact of Lower Jurassic Inklin Group (Laberge Group) sediments and metasediments on the south, and Mississippian to Triassic sediments of the Kedahda Formation (Cache Creek Complex) on the north. The peridotite is an alpine-type upper Mississippian to Permian body of the Mississippian to Triassic Cache Creek Complex.

The serpentinized peridotite is at least 760 metres long (possibly up to 1 kilometre) and averages 150 metres in width. Chrysotile cross-fibres occur over the length of the band within a network of fractures. The fibre length is short, varying from hairline up to 1 centimetre. Hand specimens can contain up to 10 per cent fibres by volume. A sample of the fibre was reportedly analyzed, giving indications of high-quality asbestos.

Prospecting and magnetic surveys were conducted in 1971 and 1972 by Tournigan Mining Exploration Ltd. No other work has been reported.