The Lonnie occurrence is located on Granite Creek, 2.5 kilometres north of Manson Lakes and approximately 140 kilometres north of Fort St. James. A cat trail, which leads up to the zone from the Manson Creek road, begins just south of Granite Creek.
Syenite, monzonite and carbonatite occur together in single, northwest-striking sill-like horizons within uppermost Proterozoic metasedimentary rocks of the Wolverine Complex (Ingenika Group). The Ingenika Group is represented by quartzites and garnet-biotite-muscovite schists. These rocks have been metamorphosed to amphibolite grade. To the west lie rocks of the Upper Paleozoic Nina Creek Group. Both intrusive rocks and hostrocks have been deformed and metamorphosed to lower amphibolite facies. The hostrocks comprise psammitic to semipelitic mica schists, micaceous quartzites and marble, which strikes southeast (150 to 170 degrees) and dips steeply to the southwest (70 to 80 degrees on average). The various rock units within each intrusive zone are distributed in interfingering lenses. Alkali metasomatism (fenitization) can be detected for a few tens of metres beyond the intrusions. Preliminary uranium/lead systematics suggest that the Lonnie carbonatite was emplaced in the Late Devonian to Early Mississippian; interpreted zircon ages of 350 ±10 million years and 370 ±20 million years were obtained (Open File 1987-17).
Two varieties of carbonatite are present within the Lonnie complex. One is aegirine sovite in which the principal components are calcite, microcline, perthite and aegirine; the other is biotite sovite, comprising calcite, biotite and usually plagioclase. Both the biotite and aegirine sovites are variably foliated and contain apatite (up to 20 per cent), magnetite and pyrochlore as accessory minerals. The biotite sovite may also contain zircon locally; columbite, ilmenorutile and ilmenite have also been reported. The aegirine sovite occurs along the southwestern margin of the complex, the biotite sovite along the northwestern margin. The biotite sovite is variably mylonitized, with the most intense shearing near the contact with the country rocks. Enrichment in zircon, pyrochlore, columbite, pyrite and pyrrhotite has been noted near the contacts of the sovites with syenites.
Feldspathic intrusive rocks, monzodiorite, monzonites and syenites, outcrop as lenticular masses separating the carbonatite units. All phases contain accessory muscovite, biotite, calcite and apatite. Nepheline syenite is also locally present and contains significant amounts of zircon.
Pods and layers of fenite occur within the Lonnie intrusive complex. The fenite is medium- to dark-green in colour with gossanous weathering. It consists of aegirine and sodic amphibole with microcline, plagioclase and calcite in varying amounts. Trace constituents include pyrochlore, magnetite and zircon.
The host psammitic and semipelitic schists are recognizably fenitized for a few tens of metres beyond the intrusive contacts. Microcline, plagioclase and quartz are major constituents, with aegirine and arfvedsonite disseminated throughout, presumably replacing the original mafic silicate minerals. Biotite is present in trace amounts only. Calcite, apatite, magnetite and zircon may be present and coarse-grained arfvedsonite, magnetite and feldspar segregations may be developed locally.
The Lonnie carbonatite zone has been traced by surface trenching for a length of approximately 650 metres, with widths up to 50 metres. It strikes 120 degrees and dips approximately 60 degrees southwest. Inferred (possible) reserves at Lonnie are 272 000 tonnes grading 0.2 per cent niobium and up to 15 per cent zircon (Z.D. Hora, personal communication, 1991).
In 1953, Earnest Floyd first discovered carbonatite along Granite Creek while prospecting for uranium with C.S. Powney, Mr. Almond and Mr. Kay. In 1954, the first claims were staked by C.S. Powney and then sold to Kennecott Explorations. In 1955, Kennecott Explorations completed a trenching program on the property and outlined a zone, 480 by 15 metres, grading 0.15 per cent niobium (Property File Rimfire - Chisholm, E.O., 1960). A zone in the centre of the property averages 0.21 per cent niobium across a width of 7.6 metres and a length of 240 metres (Open File 1987-17). The presence of uranian pyrochlore has been determined from x-ray work by R.M. Thompson (Minister of Mines Annual Report 1954, page A97).
In 1969, Westrim Mining Corp. acquired the property and resampled the 1955 trenches. In 1970, Westrim Mining Corp. dug five trenches at the southwest end of the showing.
In 1976, the claims were restaked by C.S. Powney. In 1978, Moly Mite Mines Inc. optioned the property. In 1979, Moly Mite Mines Inc. drilled three holes in the Lonnie showing but no assays were done on the core. In 1982, H.M. Jones purchased the Wolverine Group claims which encompassed the Lonnie claims. Considerable work was done on the property including mapping, silt and soil sampling and magnetic surveys.
A 1990 survey of the area revealed thorium to be the radioactive element (F. Ferri, personal communication, 1990). The property was dormant from 1991 to 2007. In 2007, Rocher Deboule Minerals Corp. staked the Lonnie property. In 2009, Rocher Deboule Minerals Corp. drilled five holes into the Lonnie 2 showing to the north but only found background values for niobium. In 2010, Rocher Deboule Minerals Corp. was renamed American Manganese Inc. and conducted soil and rock sampling on the Lonnie property. Rara Terra Minerals Corp. optioned the property in late 2010. In 2011, Rara Terra Minerals Corp. conducted an airborne magnetic survey and soil sampling.
In 2019, American Manganese Inc. conducted a 7.05 line-kilometre magnetometer geophysics survey over the Lonnie property and collected 125 soil samples and 39 rock chip samples. Niobium assays ranged from 0.58 per cent (Sample 19LON-14) to 0.0563 per cent (Sample 19LON-31; Assessment Report 38373). Soil sampling outlined a well-defined zone of elevated cerium, lanthanum, niobium, neodymium, praseodymium and yttrium.
