The Ursa property is located on Mount Bisson, 51 kilometres northwest of the community of Mackenzie.
The area lies within the Omineca Crystalline Belt, which consists of siliciclastic sediments with minor carbonates and mafic rocks. These rocks belong to the Late Proterozoic Ingenika Group. Within the Wolverine Range, the Igenika sediments are highly metamorphosed and subsequently intruded by granodioritic bodies and associated pegmatites, which are possibly early Cretaceous. These metamorphic rocks, called the Halleran Alkaline Complex, part of the Wolverine Complex, consist of amphibolite and calc-silicate gneiss, schists, micaceous quartzite, and crystalline limestone.
The Ursa showing occurs within a 10 by 2- metre zone of mylonitized, gneissic pegmatite. Coarse to fine-grained monazite is disseminated in clotty layers. The quartz is shattered and smokey. The pegmatite is bounded on the west by fine-grained radioactive syenite. Other rocks include calc-silicates with biotite, phlogopite and diopside. Four rare-earth-element minerals have been found on the property, including monazite, allanite, cerorthite and an unidentified Ba-Fe-Ree-silicate.
In 1987, a grab sample (UG-1) of the pegmatite assayed 0.25 per cent thorium, 0.59 per cent lanthanum, 0.65 per cent cerium, 0.07 per cent praseodymium, 0.44 per cent neodymium and 0.36 per cent samarium (Assessment Report 16781).
The property was discovered by prospecting in 1987 and optioned by Chevron Minerals Limited a year later. A program of rock and soil sampling, geological mapping and a 2.7 line- kilometres ground scintillometer survey was completed at this time. In 1989, a program of rock sampling and geological mapping was completed. In 1996, Argonauts Group completed prospecting and geological mapping on the area as the ERZ claims. During 2006 through 2011, Paget Minerals completed programs rock and silt sampling, geological mapping and a combined airborne magnetic and radiometric survey, totalling 564.4 line-kilometres, on the area as the Mount Bison property.
