The MacDonald Asbestos occurrence is located north east of Big Onion Lake.

In 1961, Kerr Addison Gold Mines completed a program of prospecting, geological mapping and a magnetometer survey.

Locally, two areas of serpentinized peridotite, approximately 3.2 kilometres apart, hosts hairline to 0.8 centimetre long asbestos fibres occurring as roughly 1 per cent of the host rock (Property File: Kavanagh, P.M.,1961).