The Millsite showing is located near a sawmill on the north side of Brandywine Creek, approximately three kilometres north of Brandywine Falls in the Pacific Ranges.

The elongate, northwest trending Callaghan Creek roof pendant comprising Lower Cretaceous Gambier Group volcanic and sedimentary rocks underlies the region. The Millsite showing occurs within greenstones at the western edge of the roof pendant near a small body of hornblende diorite of the Jurassic to Tertiary Coast Plutonic Complex.

Mineralization consists of sphalerite, galena and less abundant chalcopyrite in veins and stringers hosted by greenstone. Stockwork chalcopyrite mineralization is also present within a pod of hornblende diorite.

A 1974 drill hole (MC4) intersected 1.5 metres of sheared dacite grading 6.17 grams per tonne gold, 517.7 grams per tonne silver, 1.2 per cent zinc, 0.44 per cent lead and 0.01 per cent copper. (Assessment Report 5405).