The Caledonia claim Lot 1756 located on the northwest slopes of Castle Mountain is centred on dunite of the Carboniferous to Permian Mount Roberts Formation. The ultramafic rock carries finely disseminated nickel sulphides (inferred to be pentlandite), chromite and magnetite.
In 1939, a shipment of 14 tonnes of ore yielded 156 grams silver and 249 grams gold. In 1972-73, Hunter Point Explorations Ltd. drilled four surface diamond-drill holes totalling 274 metres.