The Loon Creek diatomite showing is located in Loon Creek valley 5 kilometres southwest of Loon Lake and 13 kilometres east-southeast of Clinton.

The occurence is hosted in the north draining Mio-Bonaparte channel, a fluviatile and lacustrine interlayer of the Miocene Deadman River Formation which is part of the Miocene to Pleistocene Chilcotin Group composed mainly of alkaline plateau basaltic flows. The Deadman River Formation (EMPR Open File 1989-21) is composed of rhyolite ash, tuffaceous sandstone, siltstone, shale, minor pebble conglomerate. The siltstones and shales are commonly carbonaceous and/or diatomaceous.

The Loon Creek diatomaceous earth showing is exposed in a 2 metre high roadcut near the base of a Miocene channel filling of fluviatile and lacustrine sediments occupying the Mio-Bonaparte Channel which is over 5 kilometres wide and 400 metres deep. A 3 metre thickness of fairly pure diatomite is exposed for 60 metres along a cut on Loon Lake Road.