The Rancheria occurrence is located 17 kilometres southeast of Rancheria, 3.5 kilometres south of the Yukon border, on a branch of the Tootsee River.

The area is underlain by northeast trending Cambrian to Devonian sediments intruded by quartz monzonite of the Early Cretaceous Cassiar batholith. The sediments, dipping 40 to 50 degrees southeast, comprise black and grey limestones and light and dark quartzites. The sediments are possibly part of either the Cambrian-Ordovician Kechika, Ordovician-Silurian Road River, Middle-Upper Devonian McDame or Silurian-Lower Devonian Ramhorn groups. These are altered to biotite-carbonate hornfels and garnet-diopside skarn adjacent to the batholith. The width of the skarn alteration, exceeding 1 kilometre in places, suggests that the quartz monzonite dips southeast under the sediments.

Tremolite and wollastonite mineralization outcrop 600 to 900 metres southeast of the quartz monzonite. A zone of tremolite diopside-carbonate skarn outcrops over a strike length of 825 metres, varying up to 250 metres in width on surface. It is comprised mostly of tremolite with some outcrops containing actinolite, diopside and wollastonite, at the northern end. This skarn is interbedded with quartzite along its northwest edge and bounded to the southeast by a diabase dike. Wollastonite-bearing skarn outcrops over a strike length of 630 metres in a narrow zone along the southeast contact of the same dike.

A second zone of tremolite-diopside-carbonate skarn, 850 metres long, outcrops along strike 1500 metres southwest of the first zone. Surface widths vary up to 350 metres. Several westward trending diabase dikes, up to 35 metres wide, cut this zone. The skarn is comprised mostly of tremolite with minor actinolite and diopside. It is interbedded with quartzite to the northwest and flanked by grey limestone to the southeast. Wollastonite is present in the limestone south of the skarn zone, adjacent to a diabase dike.

Erratically mineralized quartz veins, 0.01 to 1 metre wide, occur in the intrusive rocks and contain molybdenite. The skarns contain disseminated scheelite, molybdenite and powellite, which are often associated with fractures. One brecciated chert-carbonate zone adjacent to the intrusive rocks contains blebs of galena and sphalerite.

Highest results from grab samples from the best showings discovered to date (ca. 1979) are 0.11 per cent molybdenum and 0.72 per cent WO3 (Assessment Report 7673).

In 1979-80, small programs of linecutting, geological mapping and geochemical soil sampling (870 samples) was carried out on the Rancheria property by Noranda Exploration Company, Limited.