A 520-metre thick bed of limestone outcrops on either side of the head of Kumealon Inlet, on the east side of Grenville Channel, about 54 kilometres south-southeast of Prince Rupert.
The limestone is situated in a sequence of metasediments comprising a roof pendant within the Jurassic to Tertiary Coast Plutonic Complex. The bed is bounded to the southwest by fine grained biotite schist and to the northeast by locally dioritized greenstone schist. The deposit strikes 120 degrees for at least 6.5 kilometres and dips 55 to 90 degrees southwest.
The bed is composed mostly of fine to coarse grained, white and bluish grey, high calcium limestone with some thin beds and lenticular masses of dolomite. The limestone becomes pyritic and interbedded with schist, over a 9 metre width, on the southwest margin of the deposit. Several inclusions of mica schist and igneous rock, up to 9 metres thick, occur within the limestone. A chip sample, taken over a 27.4 metre thick band of coarse grained, white limestone near the northeast edge of the deposit, assayed 52.35 per cent CaO, 2.07 per cent MgO, 1.04 per cent Si02, 0.18 per cent Al2O3, 0.14 per cent Fe2O3 and 0.04 per cent sulphur (CANMET Report 811, page 176, Sample 36A).
Previous prospecting outlined a zone of purer limestone outcropping along the southwest shore of Kumealon Lagoon, 1000 to 2200 metres northwest of the head of Kumealon Inlet. The zone is comprised mostly of white, recrystallized, fine to coarse-grained limestone with some blue to grey, coarse-grained limestone and minor dolomite as lenses, streaks and beds up to 0.3 metre thick. The zone strikes 150 degrees for at least 1200 metres and dips vertically to steeply southwest. The bed is estimated to have an average stratigraphic thickness of 180 metres. The limestone contains minor fine grained, disseminated pyrite and rare tremolite. No dikes are evident within this zone. Eight, 3.05-metre chip samples taken in succession across a face parallel to the shore, averaged 55.06 per cent CaO, 2.11 per cent insolubles and 43.51 per cent ignition loss (Industrial Mineral File - C.D. Bown, 1958, Samples A to H). The zone is estimated to contain 19 million tonnes of limestone over a strike length of 1200 metres, with an average width of 180 metres and an average height above water of 30 metres (Industrial Mineral File - C.D. Bown, 1958, page 7).
In 1958, the deposit was examined by Columbia Cellulose Co. Ltd. of Prince Rupert during a search for local limestone sources.
In 2016, Durango Resources Inc. holds the Smith Island (103J 012) and Mayner's Fortune (103I 113) limestone projects. The company is conducting its first phase exploration program on its limestone properties, which is expected to include sampling to test for limestone quality and mapping to confirm the historical reports. The company is also investigating the Kumealon Inlet Limestone deposit for its potential.
