The showings are located on the southeast coast of Moresby Island, on the ridge between Ikeda Cove and Collison Bay, about 0.8 kilometre west of this Bay. The elevation is between 183 and 366 metres above sea level.

The showings were discovered in 1907 by Ike Thompson and C.T. Daykin. In 1914, the Sadie claim, Lot 2610, was Crown-granted to Thompson; the Thunder, Lot 2611, to Thompson and J.S. McMillan; the Spade Flush, Lot 2612, to Thompson and B. Metcalfe. These claims formed the Thunder Group covering 81.15 acres. The property was worked until the mid-1920's with surface stripping and the driving of a 91-metre adit on the Thunder claim in 1913-1914. During 1921 the group was optioned to Seattle interest.

In 1968 the Thunder claim was held by Mrs. Sadie Thompson and the McMillan estate, each having one-half interest. The other claims are part of a large block held by Falconbridge Nickel Mines Limited (See Lily, 103B 028).

Recent exploration has mainly involved examination and magnetometer surveying, first by Falconbridge Nickel Mines Limited and then by The Granby Mining Company Limited and Jedway Iron Ore Limited. Basalts of the Vancouver Group, Upper Triassic Karmutsen Formation are conformably overlain by limestone and argillites of the Jurassic to Triassic Kunga Group. The limestone strikes about 030 degrees and dips gently west. The rocks are intruded by northeast striking, steep east dipping diorite, felsite and basalt dikes.

Magnetite, with variable pyrite, chalcopyrite and garnet-rich skarn, occur as conformable tabular bodies and as dike-like bodies, near normal to stratification. Mineralized zones occur in three areas. All zones are composed of mixtures, in varying degrees, of magnetite and garnet-rich skarn with epidote and chlorite. In some places chalcopyrite and pyrite form significant concentrations.

At the adit zone, a skarn and magnetite lens, 64 metres long and up to 6 metres wide, occurs within greenstone. The lens strikes 030 degrees and dips about 65 degrees west. About 400 metres to the west, a zone 150 metres long and up to 30 metres wide contains skarn and magnetite replacing Sadler Formation limestone at the Karmutsen contact. About 150 metres northwest of the adit are two distinct mineralized bodies, one an equant-shaped body up to 30 metres long, and another 35 degrees striking dike-like body, 60 metres long and 3 to 6 metres wide. A 2-metre adit sample assayed 2.6 per cent copper, 103 grams per tonne silver and 1.4 grams per tonne gold (Minister of Mines, Annual Report 1918, page 44).

Inferred reserves are 172,365 tonnes with 35.0 to 50.0 per cent iron (Energy, Mines and Resources Canada Reserves File - Thunder).