The Nancy occurrence is located approximately 2 kilometres south of the British Columbia-Yukon border and 13 kilometres south of Milepost 710 on the Alaska Highway, just north of the Tootsee River.
Cambrian-Ordovician Kechika Group sediments have been intruded and hornfelsed by Early Cretaceous quartz monzonite of the Cassiar batholith. Calc-silicate hornfels units adjacent to the batholith are cut by quartz veins and contain garnet-diopside-idocrase-calcite skarn zones with minor pyrrhotite and scheelite.
Three main types of mineralization occur: 1) molybdenite mineralization usually occurs in or closely associated with quartz veins in strongly fractured, sericitized zones cutting quartz monzonite. Most mineralized veins occur within a 100 metre wide zone along the intrusive-hornfels contact. The predominant attitude of the veins is 340 to 360 degrees dipping vertical to 80 degrees west. Veins vary from 1 centimetre to 1.5 metres wide with 5-10 centimetres being most prominent. Most large veins can be traced along strike up to 100 metres but pinch and swell and have erratic mineralization. No significant mineralization has been traced beyond 100 metres from the contact (ca. 1979). 2) Scheelite occurs in minor concentrations throughout the calc-silicate hornfels-skarn unit. 3) Galena, sphalerite and pyrite occur in narrow crystalline quartz veins and breccia zones associated with shear zones.
Results from exploration work in 1978-79 indicate that significant molybdenite mineralization is confined to an area approximately 100 metres wide and less than 400 metres long along the intrusive-hornfels contact.
In 1978-79, Noranda Exploration Company, Limited conducted soil sampling, geological mapping and diamond drilled one BQ diameter hole totalling 124.37 metres. A pervasive clay-carbonate alteration zone that grades into an aplite zone with a quartz vein containing high-grade molybdenite was intersected. A sample (P1834) across 1.57 metres (103.43-105.0 metres) of the zone containing the mineralized quartz vein assayed 0.513 per cent molybdenum, 0.04 per cent tungsten and 0.6 gram per tonne gold (Assessment Report 8125).
