Geology of the Ormsby Deposit

The Ormsby Deposit is exposed on surface, in the Ormsby decline, in subdrifts, in crosscuts and in drill core. The presence of gold mineralization can be recognized by the coincidence of sulphides and silicification in weakly foliated but strongly lineated hydrothermally brecciated metavolcanic amphibolite. Pyrrhotite is dominant and occurs with lesser pyrite in variable proportions as disseminations, veinlets, semi-continuous streaks and irregular clots in amphibolite and as a minor constituent of quartz veinlets. Minor subhedral to euhedral arsenopyrite occurs as disseminations, blebs and streaks in amphibolite breccia proximal to quarts veins, in narrow quartz veins and in quartz blebs. Chalcopyrite, sphalerite and galena have been observed but are rare. Quartz is an important but minor component by volume of the mineralized zones. Silicification is post to late-tectonic and occurs as discrete, discontinuous light to dark gray quartz veins, pods, or disseminations that cut foliated and brecciated amphibolite. Visible gold occurs as isolated grains in quartz veinlets, and proximal to sulphide clots in quartz veinlets. Gold grains are also disseminated with sulphides in amphibolite breccia.

Geology of the Nicholas Lake Deposit

Granite and granodiorite plutons, plugs and dykes are common throughout the region. A small granodiorite plug is the host for the gold veins of the Main Showing. Auriferous quartz-sulphide veins of the Main Showing occur in shears zones within, and on the southern margin of a 200 to 300 metre diameter granodiorite intrusive. Thirteen veins of variable continuity and grade have been recognized. The main auriferous veins on surface occur along the south border phase of the granodiorite in migmatite or in hornfels. At depth, however, drilling indicates that most of the veins occur well within the granodiorite body itself. The quartz-sulphide veins are mostly vertical but can dip to 80º in either direction. Sulphides comprise roughly 6% of the veins and include arsenopyrite, pyrite, pyrrhotite, sphalerite, galena and minor chalcopyrite in decreasing order of abundance. Gold occurs as grains about 5 to 30 µ m in size and is closely associated with fractures and open space fillings in sulphides or alone within quartz.