The J and S occurrence is located on the eastern shore of Henderson Lake, approximately 3 kilometres north of Snug Basin.

The area is underlain by a north trending band of Upper Triassic Vancouver Group, Quatsino Formation limestone. This narrow limestone band is in contact to the west with basalt of the Karmutsen formation (Vancouver Group), and to the east with Lower Jurassic volcanics of the Bonanza Group. The strata is intruded by diorite and granodiorite of the Jurassic Island Plutonic Suite. Mafic dykes are also observed in the area.

Locally, magnetite occurs as massive lenses and disseminations in an altered rhyolite (fine-grained diorite). Disseminated chalcopyrite and pyrite occur with the magnetite. Skarn minerals present include epidote and garnet. The Florence occurrence, in the same vicinity, is reported to have a lead of high grade copper ore (Minister of Mines Annual Report 1898).

The area was originally explored in 1899 and 1916. In 1965, Alberni Mines completed a program of geological mapping, geochemical sampling and a ground magnetometer survey. In 1967, Mt. Agnes Mines completed a ground magnetometer survey and five diamond drill holes on the Rainy Day claim. In 1969 and 1970, Nootka Explorations completed a program of rock and soil sampling, geological mapping and a ground magnetometer survey on the area as the Henderson property. A sample taken across 3 metres of magnetite formation assayed 37.80 per cent iron, 0.10 per cent titanium (TiO2), 0.15 per cent copper and trace gold and silver (Prospectus: Alberni Mines Ltd., 1965).

In 1980, the area was prospected by A. Ingelson and L. MacEachern. Chip samples assayed up to 1.3 per cent copper and 45.69 per cent iron (Assessment Report 8898).

In 2007 through 2013, Nahminto Resources completed a program of prospecting, geological mapping, geochemical sampling, a ground magnetometer survey and airborne geophysical surveys on the area as the TJM claims, apart of the Nahmint property.