The Oppenheim chromite showings are in a small gully that opens up on the west side of the old Cariboo Wagon Road, southwest of Cache Creek. Only a small amount of development was done in the early part of this century and the condition of the showings are now unknown.

The hostrock for the chromite prospect is projected to be serpentinite of the middle Pennsylvanian to Upper Triassic eastern facies of the Cache Creek Complex. This consists of a Late Triassic accretionary prism/subduction complex associated with the Nicola volcanic arc. The melange contains Pennsylvanian and Early Permian limestones, chert, basalt, argillite and ultramafic rocks in a matrix of Permo-Triassic chert and argillite.

At the Oppenheim showing, alternating bands of serpentinite and sediments, several metres thick, are exposed in a gully. The general strike of the rocks is northwest with an approximate 45 degree southwest dip. The serpentinite is extremely sheared, creating abundant flake talus in the gully. Contacts between the serpentinite and the sediments have not been seen. The chromite occurs as massive pods and is described as finely crystalline containing some pyrite along seams.

Trenching in 1918 and 1939 to 1941 exposed two chromite showings. A chip sample taken across the width of a chromite lens assayed 37.1 per cent Cr2O3 (Stevenson, 1941). In 1918, a shipment of 190 kilograms of chromite ore was sent to the Ore Dressing and Metallurgical Laboratories of the Mines Branch, Department of Mines, Ottawa, for a concentration test. Results show that practically all the chromite is freed from the gangue at 50 mesh; that a satisfactory separation can be made by water concentration on tables, resulting in a recovery of 72.7 per cent Cr203 contained in the first and second concentrates which averaged 45.8 per cent Cr203. Both grades of concentrates are metallurgical products and can be used for reduction to ferro-chrome, but on account of the iron sulphide present in the ore, which reports in the concentrates by water separation on tables, they cannot be classed as chemical products (Munition Resources Commission, 1920).

The showing was first discovered and staked in 1918 by Phillip Oppenheim of Ashcroft. Later that same year the showing was sampled by the Munition Resources Commission and a 190-kilogram sample was sent to Mines Branch, Ottawa, for testing; another sample was sent to the Provincial Assay Office. The ground was then restaked by R. Langdon in 1935 but there are no records of work done, if any. The showing was held from about 1937 by W.L. Starnes of Ashcroft, and J.W. Oakes of Calgary. Work carried out by A.E. Ames & associates in the period 1939-41 included a magnetic survey, prospecting and some diamond drilling; no other showings were found. In 1947, the property was held by Mr. Oakes as the Mac, Stan and Mae claims; a magnetic survey was carried out. Mariner Explorations Inc. acquired the property, Mariner claim, in about 1982; bulldozer trenching was reported. Cardinal Mineral Exploration optioned the property in December 1986 and carried out magnetic and gravimetric surveys.