The Greenstone Creek occurrence is described as being located on or near Greenstone Creek, approximately 2.1 kilometres below the Big Mike (MINFILE 092F 237) past producing mine.

The area is underlain by Karmutsen Formation volcanics overlain by Quatsino Formation limestone, both of the Upper Triassic Vancouver Group. These in turn are overlain by volcanic flows and breccias of the Lower Jurassic Bonanza Group. Intruding the stratigraphy are plutonic rocks of the Lower to Middle Jurassic Island Plutonic Suite. These plutonic rocks on Vancouver Island vary in composition from gabbro to quartz monzonite but are mainly granodiorite and quartz diorite.

Locally, banded, silicified, and otherwise altered, crystalline limestone outcrops for 7.5 metres near the creek edge and strikes north 60 degrees east with a dip of 25 degrees south east. The limestone is largely replaced by quartz, wollastonite, diopside, garnet and sulphides. Sulphide mineralization consists of sphalerite, galena, pyrite, and chalcopyrite occurring over 0.3 metre widths.

In 1965, Gunnex Limited completed a program of geochemical sampling, geological mapping and ground magnetic and electromagnetic surveys on the area as the M and Thelma claims. In 1969, Georgia Mines completed an airborne magnetic survey on the area.