The Yornoc occurrence is located 40 kilometres southwest of Invermere in the Golden Mining Division. The occurrence is near the headwaters of Ben Abel Creek, a tributary of Dutch Creek, north of Mount Abel in the Purcell Mountains.

The area is underlain by Proterozoic clastic sedimentary rocks and Cretaceous intrusive rocks. The occurrence is within the Dutch Creek Formation of the Proterozoic Purcell Supergroup. The Purcell Supergroup strata include the Aldridge, Creston, Kitchener, Dutch Creek and Mount Nelson formations (Paper 1990-1).

In the vicinity of the occurrence, rocks of the Kitchener and Dutch Creek formations have been further subdivided and assigned to the Van Creek and Gateway formations (Open File 1990-26).

The Dutch Creek Formation includes green and black laminated argillite, quartzite, siltstone and buff dolomitic siltstone. The Van Creek Formation consists mainly of coarse to medium grained, light grey to dark green quartzite, siltstone and silty argillite and correlates with the strata of the Lower Kitchener Formation.

The Gateway Formation consists of an interbedded sequence of quartzite, green siltstone and buff dolomite that correlates with the lower portion of the Dutch Creek Formation. The contact with the underlying Van Creek Formation is gradational or marked by the basaltic flows of the Nicol Creek Formation.

The sedimentary rocks have undergone regional metamorphism to at least greenschist facies.

The Yornoc occurrence consists of a number of pits that have been cut on a zone of quartz-barite veining up to 2 metres wide. The veins contain chalcopyrite, galena, and pyrite with considerable malachite and azurite. The mineralized section of this vein system extends over 500 metres. However, outcrops of vein material can be traced across an overburden-covered valley for a distance of over a kilometre (Assessment Report 2051). A grab sample collected from the vein assayed 2.73 per cent copper (Open File 1990-20).