A belt of Upper Triassic Vancouver Group, Quatsino Formation limestone up to 1600 metres wide extends northwest for 6.4 kilometres, paralleling the west coast of Texada Island, between Davie Bay and Mouat Bay. The limestone dips southwest, with underlying basaltic flows of the Upper Triassic Vancouver Group, Karmutsen Formation outcropping along the northeast margin of the belt. To the southwest, the limestone is in fault contact with the volcanics. The unit is possibly up to 300 metres thick. Diamond drilling on the Paul claim Ggoup in 1973 and 1974 intersected up to 100 metres of limestone without encountering the underlying volcanics. Dikes within the limestone are rare.
The limestone belt is generally composed of fine-grained, medium to light grey, high-calcium limestone frequently cut by calcite veins. Locally, tiny dolomite crystals are disseminated in the limestone. On Lot 25, high calcium limestone is found interbedded with magnesian limestone. A sample from one of these magnesian beds anlaysed 38.11 per cent CaO, 13.88 per cent MgO, 1.72 per cent SiO2, 1.03 per cent Al2O3, and 0.63 per cent Fe2O3 (CANMET Report 811, page 157). Five chip samples taken in succession over a total width of 381 metres, across the south end of the deposit, from its northeastern edge averaged 53.79 per cent CaO, 1.53 per cent MgO, 0.29 per cent insolubles, 0.24 per cent R2O3, 0.082 per cent Fe2O3, 0.005 per cent MnO, 0.015 per cent P2O5, 0.038 per cent sulphur and 44.00 per cent ignition loss (Bulletin 40, page 82).
B.C. Cement Co. Ltd. initially carried out some exploration work near the south end of the deposit in the 1950s. Canada Cement Lafarge Ltd. drilled 31 holes on the north end of the deposit near Mouat Bay in 1973 and 1974. The company conducted a total field magnetometer survey over the area of drilling in 1985 to test for deep-seated dikes and dikes on surface obscured by overburden.
CBR Cement Canada Limited engages in the manufacturing, production and sales of Portland cement, aggregates, concrete and concrete products in British Columbia and the Pacific Northwest region of the United States. The company operates a modern 1 million tonne capacity plant on Tilbury Island adjacent to the Fraser River in Delta. The plant was put into operation in 1978 and replaced an obsolete plant that was located on Vancouver Island at Bamberton, north of Victoria, on the west side of Saanich Inlet.
Extensive exploration of District Lots 573 and 589 on Texada Island has established reserves of limestone suitable for the Tilbury plant. Drillholes determined 100 million tonnes of reserves in an area 300 metres wide extending 2000 metres in a southeast direction from the proposed quarry's northwest extremity at the boundary of lots 235 and 573. The limestone consists mainly of calcium carbonate (CaCO3) in a concentration greater than 90 per cent; a deposit of massive thickness, somewhat faulted, bent and dipping to the northeast about 40 to 50 degrees. Surface samples were taken systematically over the area and cores were taken from drillholes to determine the extent of the deposit (Property File - Texada Limestone Property Report, by CBR Cement Canada Limited, circa 1990).
