The Castle Mountain property is located near the village of Harrogate in southeastern British Columbia.

The property is underlain by dolomite, limestone, shale and quartzite which range from Cambrian to Devonian age. A number of zinc-lead showings occur in dolomites of the Middle Ordovician to Silurian Beaverfoot Formation.

The general structure is that of a syncline with steeply dipping or overturned limbs, further complicated in the Castle Mountain area by the presence of several thrust and strike-slip faults.

Zinc-lead mineralization is entirely restricted to the Beaverfoot Formation, and appears to be preferentially concentrated in the upper half of the formation. Fractures resulting from dissolution and re-precipitation of dolomite are closely associated with lead-zinc mineralization. Zinc and lead occur as disseminated to locally massive hydrozincite, sphalerite and galena in dolomite breccias. Two main end member types of breccias are (1) angular dolomite clasts in a sparry dolomite matrix (associated with solution collapse structures and faults), and what has been termed "grapeshot rock"; and (2) stratabound dissolution zones up to several metres thick and laterally continuous for up to several hundred of metres along strike. Lead-zinc showings were noted in three main areas on the property.