The Golden Gate occurrence lies in the Zeballos gold camp, an area underlain by a Lower Jurassic Bonanza Group Island arc sequence of basaltic to rhyolitic volcanic rocks. Conformably underlying the Bonanza rocks are limestones and limy clastics of the Quatsino and Parson Bay formations, and the tholeiitic basalts of the Karmutsen Formation, all belonging to the Upper Triassic Vancouver Group. Dioritic to granodioritic Jurassic plutons of the Zeballos intrusion phase of the Island Plutonic Suite have intruded all older rocks. The Eocene Zeballos stock, a quartz diorite phase of the Catface Intrusions, is spatially related to the areas gold-quartz veins. Bedded rocks are predominantly northwest striking, southwest dipping, and anticlinally folded about a northwest axis.
In the Zeballos gold camp, generally narrow (10 to 30 centi- metres) quartz-calcite veins, trending north or east (Fieldwork 1983, page 230) cut all rock types. Vein mineralogy includes pyrite, sphalerite, galena, chalcopyrite and locally arsenopyrite.
Recorded production for the camp totals 9465 kilograms gold and 4119 kilograms silver, from 652,000 tonnes of ore mined (Fieldwork 1982, page 291). Most of the production came from the Spud Valley and Privateer deposits.
The Golden Gate vein, striking 340 to 350 degrees and dipping 70 degrees east follows a shear zone in massive Bonanza andesite, cut by numerous fine-grained dykes of gabbro, presumably associated with nearby Jurassic Island Plutonic Suite and the Eocene Catface stock.
The shear zone is only a few centimetres wider than the vein, which is lenticular and ranges in width from 2.5 to 20 centimetres. Vein mineralogy includes pyrite, pyrrhotite and chalcopyrite in quartz gangue. Usually, sulphides make up a few per cent of vein material but locally, this can go as high as 75 per cent.
Gold mineralogy is not known. The vein has been traced over 168 metres. Lammers (1939) mentions the "Campbell Vein" 6 metres north- east of the shaft. This vein strikes 260 degrees with a 78 degree north dip. A 0.9 metre channel sample returned 25.4 grams per tonne and vein minerals are pyrrhotite, pyrite, sphalerite, chalcopyrite and galena in crushed, leached talcose gouge, quartz and calcite.
A shipment of high grade sorted ore in 1940 produced 373 grams of gold, 156 grams of silver, with 44 kilograms of copper and 39 kilograms of lead. In 1983, diamond drilling encountered a 9.8 metre intercept of 9.6 grams per tonne gold (Diamond-drill hole #5) and a 1.5 metre section assaying 135.7 grams per tonne gold and 44.2 grams per tonne silver (George Cross Newsletter #191,#192, 1983; Northern Miner Oct.6, 1983).