The Dumas occurrence is located on the south side of Clearwater Creek approximately 9.5 kilometres northeast of Ymir.
The area is underlain by argillite, schist, sericite schist, andalusite schist and argillaceous quartzite of the Lower Jurassic Ymir Group. These have been intruded by granodiorite of the Middle Jurassic Nelson Batholith and lamprophyre dikes and sills. The contact with the Nelson Batholith is approximately 300 metres to the east of the showing.
Mineralization occurs at the contact of the argillaceous sediments and the Nelson Batholith and consists of a network of quartz veins hosted in argillites and containing galena, sphalerite and tetrahedrite.
Locally, two drifts have been developed on a quartz veinthat varies from a few centimetres to 1.3 metres wide. The vein strikes north-south and dips 58 degrees east in black argillite and sericite schist. The vein exposed in the lower drift is highly pyritic, but the material stockpiled at the portal gave low assay values. At the upper adit, several tonnes of material are stockpiled and contain veinlets and disseminations of pyrite, galena and sphalerite and traces of tetrahedrite.
In 1982, sampling of the stockpile from the upper adit yielded from 9.9 to 74.9 grams per tonne gold and 44.8 to 788.0 grams per tonne silver (Property File - M.E. Mahar [1983-01-22]: Letter Re: 2 groups of claims in the Ymir area).
In 1987, samples from the upper adit stockpile yielded an average of 1.55 per cent lead, 1.29 per cent zinc, 62 grams per tonne silver and 16 grams per tonne gold (Assessment Report 16800). Character samples taken from the upper adit yielded up to 57.8 grams per tonne gold, 339.3 grams per tonne silver, 9.15 per cent lead and 6.55 per cent zinc (Property File - Triune Resources [1988-10-11]: Prospectus Report on the Dumas Property).
In 1988, samples from a tunnel yielded up to 133.35 grams per tonne gold, 719.9 grams per tonne silver, 21 per cent lead and 14 per cent zinc (George Cross News Letter, No.99, 1988).
In 2004, a sample (198873) collected near the Dumas adits assayed 41.3 grams per tonne gold, greater than 100 grams per tonne silver, greater than 1 per cent zinc and greater than 1 per cent lead (Assessment Report 27539).
A 1.8-metre-thick quartz vein cuts highly shattered black argillite at the western edge of the property. The vein hosts disseminated pyrite that is oxidized. The vein strikes 60 degrees and dips 52 degrees north. In 1987, a sample assayed 0.01 per cent lead, 0.01 zinc per cent, 6.2 grams per tonne silver and 0.2 gram per tonne gold (Assessment Report 16800).
The area has been explored since the late 1800s, with drifting on the vein from two adits beginning in 1898 and development work continuing through 1914.
In 1980, Cominco completed a program of geological mapping, soil sampling and a ground electromagnetic survey and re-opened the two drifts. In 1982, the area was prospected and sampled by D.G. Allen. In 1983, Winston Resources soil sampled the area. In 1986, a program of geochemical sampling and a ground electromagnetic survey was completed. In 1987, Triune resources completed a program of prospecting, geochemical sampling and a 10.6 line-kilometre induced polarization survey. They identified an anomalous zone, 914 metres long and 30 to 91 metres wide, with an indicated depth of more than 107 metres and open at both ends. The following year, three diamond drill holes were completed.
In 2004, Auramex Resource Corp. completed rock sampling in the area.
In 2018, Margaux Resources Ltd. optioned the property and completed a program of historical data compilation, re-logging of select core from the 2004-2005 drilling program, minor prospecting and rock sampling. The option was dropped in 2019.
In 2020, Rockland Resources Ltd. optioned the property and completed a program of prospecting, geological mapping, geochemical (rock, silt and soil) sampling and an airborne (drone) magnetic survey on the area as the Old Timer property. A sample (13569) of quartz vein material from a hand-picked pile on the Dumas occurrence area assayed 11.96 grams per tonne gold and 45.6 grams per tonne silver (Caron, L. [2020-12-02]: National Instrument 43-101 Technical Report on the Old Timer Property, Nelson Mining Division, Southern British Columbia, Canada).
