A band of limestone of the Upper Triassic Quatsino Formation (Vancouver Group), up to 2.5 kilometres wide, trends northward along the east side of Bonanza River and Bonanza Lake for 6.25 kilometres. To the west, the limestone is in fault contact with basaltic flows of the Upper Triassic Karmutsen Formation (Vancouver Group). An elongate stock of coarse grained, biotite quartz monzonite of the Early to Middle Jurassic Island Plutonic Suite intrudes the limestone from the southeast.

On the Doro claim, 1 kilometre north of Bonanza Lake, the strata strike north and dip 25 degrees east. Further north, bedding strikes northwest and dips moderately southwest. A west trending fault just north of the Doro claim likely separates the northern and southern portions of the deposit into two fault blocks that have rotated with respect to each other.

The deposit is comprised of an upper medium to dark grey limestone member and a lower light grey to white limestone member. The upper member is occasionally contaminated with chert nodules and minor tremolite. The lower member is fine to coarse grained and stylolitic. Thin beds and lenses of dark grey pyritic chert accompany this limestone near the south end of the deposit. The chert nodules and pyritic chert lenses become more numerous near the basalt contact and the monzonite stock. Numerous sills and dykes of aplite, diorite and amphibolite have intruded the limestone on the Doro claim. Four samples of powdered limestone from a series of percussion holes drilled in the lower member on the Doro claim averaged 53.5 per cent CaO, 0.38 per cent MgO, 2.05 per cent insolubles, 0.58 per cent R2O3, and 86.5 per cent brightness (Assessment Report 10193, p. 4). Two chip samples, taken in succession along 305 metres of road cut just east of the north end of Bonanza Lake, averaged 55.08 per cent CaO, 0.11 per cent MgO, 1.02 per cent insolubles, 0.33 per cent R2O3, 0.055 per cent Fe2O3, 0.008 per cent MnO, 0.02 per cent P2O5 and 43.55 per cent ignition loss (Annual Report 1968, p. 318, Samples 30 and 31). The Doro claim is estimated to contain 27 million tonnes of limestone in a 457 metre by 366 metre block (Assessment Report 10193)

The deposit on the Doro claim was initially quarried for dimension stone sometime before 1982, but no production figures are available. The International Marble and Stone Company drilled the deposit in 1982 and drove a 65-metre long adit on the Doro claim during a search for white limestone. Development work was discontinued after encountering grey limestone extensively contaminated by dikes. In 1988-2006, Industrial Fillers Ltd. completed numerous programs of geological mapping, sampling and diamond drilling.