The Harrison Hill (Fork) copper occurrence is located on the south side of Harrison Hill, east of Lake Errock, at an elevation of approximately 90 to 150 metres.

The area is underlain primarily by Middle Jurassic granodioritic intrusive rocks with minor remnants of Lower and Middle Jurassic Harrison Lake Formation andesites, andesite porphyry, andesite breccia and basalt.

Locally, granites and granodiorites host chalcopyrite, pyrite, bornite and sphalerite mineralization as fracture fillings and thicker seams up to 0.6 centimetre wide. Select samples of this material were visually estimated to contain up to 9 per cent copper (Property File - M.D. Kierans, Cyprus Explorations Corp. Ltd. [1968-12-16]: Geological Evaluation Harrison Hill Copper Prospect).

Another form of mineralization, noted in a trench in a quarry floor, consists of heavily oxidized pyrite and minor chalcopyrite, forming up to 30 per cent of the whole rock, in a very siliceous gangue. A select sample of this material assayed 0.35 per cent copper and 20.6 grams per tonne silver (Property File - M.D. Kierans, Cyprus Explorations Corp. Ltd. [1968-12-16]: Geological Evaluation Harrison Hill Copper Prospect).

Another chalcopyrite vein with moderate amounts of pyrite, 10 per cent, in a narrow, 20 centimetre fracture, has been identified for over 45 metres. The fracture dips 30 degrees north and strikes eastward.

In 1965, a select sample assayed 1.3 per cent copper and 11.4 grams per tonne silver (Property File - M.D. Kierans, Cyprus Explorations Corp. Ltd. [1968-12-16]: Geological Evaluation Harrison Hill Copper Prospect). Another sample (Number 2) assayed 4.28 per cent zinc, 0.56 per cent copper and 6.8 grams per tonne silver (Property File - J.B.P. Sawyer [1971-10-04]: Certificate of Assay and Letters - Harrison Hill).

The area was first staked in 1964 as the Fork claims. In 1968, Cyprus Exploration completed a program of prospecting and rock sampling.