The geology of the Lord of the Isles area is dominated by coarse-grained quartz diorite of the Paleozoic and/or Mesozoic Westcoast Complex, containing slices of metamorphic rock. Muller (Geological Survey of Canada Open File 821) has mapped a northwest trending body of limestone of similar age, in the vicinity.

This magnetite deposit occurs near the top of a south-facing bluff that is composed of limestone. The magnetite is mixed with pyrite, garnetite and limestone. By 1899, an adit had been driven north through green hornblende-rich igneous rock for about 6 metres. Limestone was encountered and the course of the tunnel was turned to the east. This course is followed for about 11 metres, driven in magnetite along a limestone wall on the north. At the face there is a winze of at least 5 metres depth.

A grab sample of the ore graded 50.4 per cent iron, 2.5 per cent sulphur, a trace of phosphorous and 10.6 per cent insoluble matter (Minister of Mines Annual Report 1916, page 292).