The Promise showing occurs in the northwest corner of Porcher Island, a few hundred metres northwest of the Edye Pass Mine (103J 015).
A sheared quartz vein, 30 centimetres wide, strikes east and dips 60 degrees south within Cretaceous to Tertiary quartz diorite of the Coast Plutonic Complex near its contact with Paleozoic-Mesozoic metasediments. Mineralization consists of blebs and streaks of auriferous pyrite.