The Dahl Lake occurrence is located immediately north of the east end of Dahl Lake, approximately 38 kilometres southwest of Prince George.
A northwest trending wedge-shaped area of Upper Permian limestone of the Carboniferous to Jurassic Cache Creek Complex (Group), up to 2.8 kilometres wide and 4.3 kilometres long, outcrops along the northeast side of Dahl Lake, 35 kilometres southwest of Prince George. The northeast margin of the deposit is faulted against Upper Triassic to Lower Jurassic argillite, greywacke and andesitic to basaltic volcanics of the Takla Group of the Quesnellia Terrane. To the west and south, the limestone is buried under glacial till. Bedding generally dips steeply west to vertical, although at one point it strikes 125 degrees and dips 71 degrees northeast.
The limestone is black to light grey and medium to fine-grained with abundant crinoid remains. In thin section the rock displays a few rounded quartz grains and some thin quartz veinlets. The limestone occasionally contains northwest trending chert bands up to 0.6 metres wide that sometimes form zones of numerous bands up to 9 metres wide. Cream-coloured masses of magnesian limestone are sometimes present.
A sample composed of chips taken at 1.5 metre intervals across the top of the Number 1 Quarry for 33.5 metres analyzed 55.03 per cent CaO, 0.14 per cent MgO, 0.77 per cent insolubles, 0.15 per cent R2O3, 0.06 per cent Fe2O3, trace of MnO, 0.04 per cent P2O5, 0.003 per cent sulphur and 43.48 per cent ignition loss (Geology, Exploration and Mining in British Columbia, page 395, Sample 1)
Limestone has been produced from three quarries just north of Dahl Lake by Kokanee Contracting since 1968 for pulp mills in the vicinity of Prince George. Up to 1988, a total of 550,309 tonnes of limestone were quarried. The quarry was last operated in 1990.
The Dahl Lake operation re-opened recently, processing approximately 20,000 tonnes of decorative aggregate from old waste rock (Information Circular 1996-1, page 9).
Work History
In 1981, Northrock Industries Ltd. conducted trenching and stripping of overburden on the Excalibur claims. Ten percussion drillholes in two locations were completed for a total of 105.2 metres. Drilling intercepted undescribed silver mineralization in holes 81E-7 and 81E-8. No assays were reported.
The Excalibur claims cover a limestone deposit owned and operated by Kokanee Contracting Ltd who have supplied processed limestone to the local pulp mills for approximately 23 years (as of 1991). Thirty-one percussion drill holes with 75 mm diameter were collared in limestone and drilled for a total length of 283.34 metres. These holes were drilled to a depth of 9.14 m each. No intersections of greenstone or porphry dykes were encountered which have been noted in the area. In 1990, Kokanee drilled Sixteen percussion drill holes for a total length of 244 metres.
In 1998 Northrock Industries reported limited sales to supply small contracts, although no production occurred in that year. In 2000, Northrock Industries Ltd. provided a limited amount of limestone from its Dahl Lake quarry for local rip-rap and landscape uses.
In 2011 and 2012, 0902744 BC Ltd. completed programs of geochemical (rock and silt) sampling, trenching, a 12.0 line-kilometre ground magnetic and induced polarization survey and a 296.0 line-kilometre airborne magnetic and radiometric survey on the area immediately east as the Green Gold property. A rock sample (1146543) taken from a 2- to 3-metre wide epidote-chlorite–altered dike with malachite cutting limestone in the Dahl Lake quarry assayed 0.36 gram per tonne gold, 6.6 grams per tonne silver and 0.4 per cent copper (Assessment Report 33998).
