A shale deposit was worked by the Gabriola Island Shale Product Company on the northeast shore of False Narrows, near the southwest end of Gabriola Island. No production figures are available.

Shale on Gabriola Island is part of the Upper Cretaceous Nanaimo Group, Northumberland Formation. The Northumberland Formation con- sists of shales, sandstones and conglomerates with shales occurring at the top and bottom of the formation. The quarried shale belongs to the bottom portion of the Northumberland Formation.

The quarry is located within the weathered part of the lower shale and averages about 4.6 metres in thickness. The shale ranges from blue to brown in colour and shows good to moderate plasticity. Good-quality dry-press brick was made from this surface shale. Anal- yses of samples of the shale used in the brick-making machines in 1918 were reported to average about 55.6 per cent silica, 10.1 per cent ferric oxide, 20.0 per cent alumina, trace lime, 0.3 per cent magnesia, 0.1 per cent sulphur, 4.9 per cent alkalies and 9.0 per cent ignition for the blue shale (Minister of Mines Annual Report 1918, page 280).