The Zeolitic Group is underlain by Lower Jurassic Hazelton Group volcanics (Nilkitkwa Formation). The host rock is reddish-brown, amygdaloidal rhyolite flows which exhibit a poorly defined flow structure that strikes 040 degrees and dips 25 degrees southeast. A narrow shear zone in the rhyolite, striking 225 degrees and dipping 75 degrees southeast, is sparsely mineralized with pyrite and chalcopyrite.