The Highland Valley porphyry copper district occupies the western portion of the map where copper deposits lie within the Late Triassic Guichon Creek batholith. The batholith intrudes sedimentary and volcanic strata of the Mississippian to Triassic Cache Creek and Upper Triassic Nicola groups and is unconformably overlain by sedimentary and volcanic strata ranging in age from Lower Jurassic to Middle Tertiary. Two major past producing mines include Bethlehem (092ISE001) and Highmont (092ISE013). Nearby, the JA deposit (092ISE149) has measured geological reserves of 286 million tonnes grading 0.43 per cent copper and 0.017 per cent molybdenum.

The remainder of the map area is predominantly underlain by Nicola Group volcanic, sedimentary and intrusive rocks overlain by extensive Quaternary cover. Numerous copper occurrences are predominant in the Nicola Group.

The Swakum Mountain area is noted for polymetallic skarn-type mineralization, lead-zinc-silver bearing quartz veins and replacements, and polymetallic-precious metal quartz veins in Nicola Group rocks. Limited past production has been recorded at the Lucky Mike (092ISE027), Old Alameada (092ISE094) and Thelma (092ISE101). In the Stump Lake area Nicola Group rocks host numerous polymetallic-precious metal quartz veins (Enterprise (092ISE028), Joshua (092ISE109)) which have also received limited past production.

In the Merritt area, the Merritt Coalfield (092ISE058) occurs in Eocene Coldwater Formation sediments. The area is a past producer and hosts an estimated 18 million tonnes of high volatile bituminous B rank coal.

Skarn-type mineralization is also prevalent where Craigmont Mines (092ISE035) milled 34 million tonnes of copper-iron ore before closing in 1982. Recent exploration is focussed on epithermal-style mineralization (Redbird (092ISE179)) in Nicola Group volcanics.

Industrial mineral occurrences have also been identified: bentonite at Quilchena (092ISE) and Coutlee  (092ISE); gypsum at Merritt Gypsum (092ISE); and limestone at Promontory (092ISE144) and Nicola Lake (092ISE145).

BC Geological Survey Publications for NTS 092I