The Rimrock occurrence is located on an un-named tributary of Caithness Creek, approximately 3 kilometres northwest of Elko.
The area is underlain by sediments of the Helikian Purcell Supergroup which includes Gateway Formation argillite, siltone, quartzite and dolomite, and Phillips Formation quartzite, argillite and siltstone.
A quartz-siderite-calcite vein is hosted by black argillites of the Gateway Formation. The sediments strike 280 degrees and dip 30 degrees northeast. The vein is up to 1.22 metres wide and strikes 055 degrees with a vertical dip. Mineralization in the vein consists of chalcopyrite, sulphides(?) and some malachite staining. Some fault gouge occurs on the vein margins. Elsewhere, hematite has been reported to occur with chalcopyrite.
Development in the 1800s included two adits separated by about 64 metres vertically. Some shipments were made from these workings. From 1916 to 1918, 207 tonnes were mined, producing 7757 kilograms of copper and 124 grams of silver (BC METAL MM00524).
The workings include the upper adit which was driven 91 meters on a quartz-siderite-calcite vein which contains copper, silver, and gold values. The vein has been exposed by trenches and open pit. It strikes north 55 degrees east and is vertical. The wall rock is light grey Gateway silicified argillite. From the tunnel a 10.7-metre stope was mined from the back up 9 meters, and a winze sunk 12.2 metres. The mineralized vein is evident both at the bottom of the winze and the top of the slope over a width of 1.22 meters.
Grab samples from the vein in an upper adit assayed a high of 3.4 per cent copper and 9.94 grams per tonne silver (Assessment Report 19227).
WORK HISTORY
In 1987, two percussion holes were drilled on the northwest corner of the Elderberry #4 claim on behalf of R.H. Stanfield. (Assessment Report 16448). One hole was completed at 19.2 metres depth in overburden. The other penetrated 18 metres of overburden and 38.6 metres of bedrock composed of light to dark grey banded argillite. No mineralization or assays were reported.
In 1988, rotary drill hole E-4-E-1-88 was drilled in the central area of the Elderberry #4 claim to a depth of 54.8 metres on behalf of R.H. Stanfield. (Assessment Report 17934). The object of the drilling was to acquire bedrock information westerly from the Rimrock mineralized zone. Drill hole E-4-E-1-88 was located about 800 metres west of the Rimrock showings. The hole was abandoned in overburden at a dept of 54.8 metres because of drilling difficulties.
In 1989, a drilling program consisting of 2 rotary drill holes on the Elderberry #4 was conducted on the Elderberry 1A and 2A groups for R.H. Stanfield, with the object of finding a possible extension of the Rimrock copper, silver, and gold showings (Assessment Report 19227). During this program, hole D 3-1-89 was located in the central northern area of the Dogwood 3 claim, and four holes were drilled in the northeast quarter of the Elderberry 4 claim in the area of the Rimrock workings, designated as numbers Rotary holes 3-1-89; PR 1-89, PR 2-89, PR 3-89, and PR 4-89 were drilled to acquire overburden and bedrock information. Quartz veining and stringers with limonite staining was encountered in the holes but economic sulphides were not. Drill material was not assayed.
In 1997, a helicopter borne DIGHEM multi-frequency EM and magnetic survey over the Rimrock group of four claims was conducted on behalf of the R.H. Stanfield group (Assessment Report 25193). No anomalies in the survey block typical of massive sulphide responses were found. The survey was successful in locating moderately weak or broad conductors which may warrant additional work.
