At the Wallinger showing, a bed of coarsely crystalline, light creamy grey magnesite, approximately 45 metres thick, occurs within the Lower Cambrian Cranbrook Formation. Near the basal and upper contacts, the layer contains quartz and calcite but usually has a core zone of about 12 metres thick of relatively pure magnesite. The magnesite weathers to a rough surface with a light buff colour.

The magnesite grades upwards into a series of green quartzites with well-rounded quartz grains; accessory minerals include chlorite, serpentine and talc with minor hematite, sphene and zircon. In general it overlies light colored quartzites but in the Boulder- Wallinger creeks area these basal quartzites are, at least in part, replaced by coarse conglomerates resting unconformably on the Siyeh or Gateway formations.