The Gyll occurrence is located near the confluence of Gyllenspeth (GyllenSpetz) Creek and the Talchako River.

The region is underlain to the west by the Coast Crystalline belt and to the east by Mesozoic and Tertiary volcanic and sedimentary rocks. A hybrid zone along the eastern margin of the Coast Crystalline Belt contains elements of both terranes. In this zone Mesozoic rocks have been incorporated into the plutons and are overlain by Tertiary volcanic rocks. The degree of metamorphism and deformation of the Intermontane Belt supracrustal rocks increases towards the Coast Crystalline Belt.

Locally, an amphibolite-migmatite brecciated gneiss has been intruded by a quartz diorite stock and hosts a zone of quartz-sulphide (chalcopyrite-sphalerite) stockwork. Samples are reported to have yielded up to 2.5 per cent copper and 2.5 grams per tonne gold with anomalous values in zinc, strontium, vanadium and chromium (Property File - Jacques Houle [2002-10-03]: Houle Weekly Report - GYLL).

The area was discovered and prospected in 2002 as the Gyll property. No assessment reports were submitted.