The Nithi Mountain occurrence is located on Nithi Mountain approximately 10 kilometres south of the village of Fraser Lake and Highway 16. This village is about 158 kilometres by road west of the city of Prince George.
The region in which the Nithi Mountain showing occurs is within the Intermontane Belt, underlain dominantly by Lower to Middle Jurassic volcanic and sedimentary rocks of the Hazelton Group. These assemblages are overlain by the Upper Cretaceous to Lower Tertiary Ootsa Lake Group and Miocene plateau basalt. Intruding Lower Jurassic rocks of the Hazelton Group in the northeastern part of the map sheet is a belt of granodiorite, diorite and quartz diorite plutons of the Lower Jurassic Topley Intrusive Suite. Felsic plutons, probably Cretaceous, intrude both Lower and Middle Jurassic Hazelton strata.
The Topley Intrusive Suite ranges in composition from diorite to alaskite but consists mainly of quartz monzonite and diorite. In the area of the showings, two main intrusive phases have been recognized: the Nithi quartz monzonite and the Casey quartz monzonite to alaskite.
Mineralization consists of molybdenite in quartz veins up to 1 metre wide in Nithi quartz monzonite. Also in the area is a north striking, west dipping rhyolite porphyry dike which hosts secondary uranium minerals of autunite, torbernite and sabugalite along its western margin. This uraniferous zone is about 70 metres long. A sample of the porphyry dike assayed 0.14 per cent uranium (Minister of Mines Annual Report 1955, page 28). Molybdenite mineralization occurs in quartz monzonite along the eastern side of the dike in a 065 degree striking fracture but the relationship of this molybdenite occurrence to the adjacent uranium mineralization is not known.
Wallrock alteration associated with molybdenite mineralization comprises intense argillic alteration and minor amounts of weak potassic alteration.
During 1952 through 1956, American Standard Mines completed programs of trenching and four shallow drill holes, totalling 100 metres, on the area.
In 1963 and 1964, R and P Metals Corp. Ltd. (Fraser Lake Mines) conducted programs of trenching, soil sampling and limited diamond drilling on the area as the Molly claims. Drilling on the Gamma zone is reported to have yielded up to 0.10 per cent molybdenum over 117 metres in hole N-14 (Dawson, K.M. (2007-04-21): Review of the Drilling on the Nithi Mountain Molybdenum Property). Also during this time numerous other companies staked and explored the Nithi Mountain area including New Indian Mines Ltd., Jodee Mines Ltd., Dundee Mines Ltd. and Fort Reliance Minerals. The properties were later dropped by the late 1960s.
During 1970 through 1973, Nithex Exploration and Development re-staked the area and completed a program of soil sampling and four winkie drill holes. Drill hole N-4 is reported to have intersected 13.2 metres averaging 0.16 per cent molybdenite (Dawson, K.M. (2007-04-21): Review of the Drilling on the Nithi Mountain Molybdenum Property).
In 1975 and 1976, Amax Potash Ltd. optioned the Nithex claims and conducted a program of geological mapping, soil sampling, geophysical surveys and 12 percussion drill holes, totalling 975 metres. The claims were subsequently dropped.
In 1980 and 1981, Rockwell Mining Corp. optioned the claims and carried out a program of geochemical sampling, geological mapping, prospecting and diamond drilling, totalling 1818 metres. Drilling is reported to have yielded intercepts including 0.060 per cent molybdenite over 52 metres in hole R81-1, 0.200 per cent molybdenite over 4 metres in hole R81-2, 0.093 per cent molybdenite over 20 metre in hole R81-3 and 0.113 per cent molybdenite over 14 metres in hole R81-4 (Dawson, K.M. (2007-04-21): Review of the Drilling on the Nithi Mountain Molybdenum Property). Hole R81-1 and -2 were completed on the Gamma zone.
In 2004, Leeward Capital Corp. acquired the property (Terri claims) and since then has created a comprehensive compilation and interpretation of all existing data within a GIS database and conducted airborne magnetic and resistivity surveys, airborne gradiometer and radiometric surveys, a LIDAR survey, additional soil geochemical sampling and drill programs in 2005, 2006 and 2008.
This work defined the Alpha Trend (Beta, Gamma, Gamma Wesst, Delta, Theta and Sigma zones) of molybdenum mineralization that trends east- south east in a band approximately 2 kilometres wide and 4 kilometres long. The Gamma zone occurs within the Alpha Trend and comprises stockwork quartz-molybdenite veins with disseminated to massive molybdenite fractures in at least wo conjugate sets of veins in variably clay, potassium feldspar and sericite-altered Nithi quartz monzonite. Several parallel sub-horizontal molybdenite mineralized zones dip shallowly to the north east and are reported to show good continuity. The Gamma zone has been traced, by diamond drilling, for at least 700 metres along strike and to a depth of 200 metres. The Gamma West zone, located approximately 500 metres west- south west of the Gamma zone, was also identified during this time and was reported to be possible larger and more intensely fractured than the Gamma zone.
In early 2007, drilling on the Gamma zone yielded intercepts of up to 0.10 per cent molybdenite over 94.5 metres in hole N-07-17, while four holes (N-07-24, -25, -26 and -29) on the Gamma West zone yielded intersections of 0.05 to 0.07 per cent molybdenite over intervals of 21.3 to 36.6 metres (Dawson, K.M. (2007-04-21): Review of the Drilling on the Nithi Mountain Molybdenum Property).
In 2008, Leeward Capital Corp. released resource estimates for the Gamma and Delta zones with a combined inferred resource for the Gamma and Delta zones of 165.250 million tonnes grading 0.026 molybdenum and an indicated resource for the Gamma zone of 55.550 million tonne grading 0.029 per cent molybdenum using a 0.020 per cent molybdenum cut-off (Stockwatch News Release September 24, 2008).
In 2011, Leeward Capital Corp. completed a 32-hole diamond drill program, totalling 6435 metres. Highlights of this program include drillhole D-11-54, which yielded 62.79 metres grading 0.119 per cent molybdenum, and drillhole D-11-56, which yielded 102.77 metres grading 0.057 per cent molybdenum (Assessment Report 32731).
In August 2011, an updated resource summary for the Delta, Gamma and Gamma West zones was reported with a total indicated resource of 147.604 million tonnes grading 0.023 per cent molybdenum and a total inferred resource of 239.588 million tonnes grading 0.020 per cent molybdenum using a cut-off grade of 0.02 per cent (MoS2) molybdenite (Mosher, G.Z. (2011-08-31): Technical Report on the Nithi Mountain Molybdenum Property).