The Longworth occurrence is located 8.8 kilometres north of the Fraser River and approximately 82 kilometres east of Prince George.
The prospect is hosted by a folded sequence of sedimentary and volcanic rocks which underlie Bearspaw Ridge. They are all, or in part, Lower Silurian in age and equivalent to the Nonda Formation.
At least four northwest trending bands of quartzite have been mapped along the western flank of Bearpaw Ridge. Thicknesses reach up to about 400 metres. The main quartzite band outlines a synformal structure open to the northwest. Rare bedding observed in outcrop dips 70 to 80 degrees east. The quartzite is very pure, massive and homogeneous. It is composed of extremely well-rounded and well-sorted quartz grains, averaging 0.5 millimetre in diameter, which are cemented by silica. The quartzite is pinkish white to buff on fresh surfaces and weathers grey to white. Impurities include muscovite in cavities, limonite on microfractures, minor calcite and possible hydrocarbons. Eight chip samples collected in 1982 by the Geological Survey Branch averaged 99.5 per cent silica (Open File 1987-15).
High purity quartzite of Snow zone has been mapped over a strike length of 400 metres and a maximum width of about 200 metres. The northwest portion Rain zone is not as wide as the Snow zone, but the southeast portion of the Rain zone has not been mapped.
In 2016, the average values from three rock chip samples from the SE Snow zone were:
98.73 per cent SiO2, 0.04 per cent Fe2O3, 0.01 per cent CaO, 0.01 per cent MgO, 0.18 per cent Al2O3, 0.08 per cent K2O, 0.08 per cent LOI, 99.17 per cent Total, and 99.56 per cent SiO2/per cent Total (Assessment Report 36446).
In the 1970s, high purity quartzite was discovered in the Sinclair Mills and Longworth area by Consolidated Silver Standard Ltd. The Longworth tenures were first staked in 1974 by Consolidated Silver Standard Mines Limited (Silver Standard) for production of ferrosilicon and silicon metal. In 1981, Silver Standard carried out a two week blasting and sampling program. In 1981-82, the British Columbia Geological Survey Branch collected samples from four of the southeastern tenures and published analytical results for eight samples which yielded SiO2 values between 98.76 and 99.40 per cent.
In 1985, Silver Standard carried out another program of blasting, trenching and sampling. In addition to the geochemical analysis of these samples, some material was also sent to the University of British Colombia (UBC) Metallurgical Engineering Lab for thermal shock testing. The samples yielded favourable results, with some exceeding Silver Standard’s metallurgical grade specifications for raw quartzite (SiO2, 99.5 per cent; Al2O3, 0.25 per cent; Fe2O3, 0.10 per cent; CaO, nil; and LOI, 0.20 per cent. Some of these samples were collected from within MGX’s current tenures (Rain and Snow zones). Thermal breakdown testing by Consolidated Silver Standard was performed on 4 by 4 by 4 inch-sized samples from Snow, Rain, Doll and Long zones was reported in Assessment Report 14815. Thermal tests performed on 16 samples of quartzite in 1985 displayed cracking in all samples at both 1000 and 1300 degree temperatures over a 2 hour period. Based on breaking into numerous pieces, a total of four samples from the Snow zone were considered not acceptable, out of 16 total samples tested at UBC Engineering Department ceramic lab, reported in Assessment Report 14815. In 1985, Consolidated Silver Standard Mines Ltd. took 42 samples of which 28 had the required chemical specifications; SiO2 was from 98.84 to 99.80 per cent and 16 samples had acceptable thermal shock results (Open File 1987-15).
In 2007, Card JM Resources Inc. staked 38 tenures surrounding the Silver Standard’s Longworth tenures. In 2008, a vertical drillhole was drilled to a depth of 100.6 metres on Tenure 559360, then logged and assayed.
In 2014, the Longworth Silica Property was acquired by Zimtu Capital Corp. (Zimtu) covering zones of high purity Nonda Formation quartzite. Dahrouge Geological Consulting (Dahrouge) and Zimtu carried out prospecting and sampling on the Longworth mineral property in 2014. Quartzite outcrops were mapped and two surface samples were collected from the property. In 2014, Dahrouge and Zimtu conducted a prospecting program within the Longworth Silica Property. A total of two hand samples were examined and collected from the northern end of the property along Bearpaw Ridge. The samples were collected from within outcrops of Nonda Formation white quartzite. In 2015, MGX Minerals Inc. performed geological mapping and geochemical sampling of the Snow zone. Results from 2015 fieldwork confirmed the presence of high purity quartzite in the northwest portion of the Snow zone, with better grade of silica in the core area of the Snow zone which also forms a resistant and competent, topographic high.
In 2016, MGX Minerals Inc. completed geochemical sampling and geological mapping on the Longworth property. Geochemical sampling was carried out on exposed surface bedrock of the southeast extension of Snow zone and the northwest extension of the Rain zone. These zones of high purity quartzite lithology are located in close proximity to historic surface sampling and trenching performed by Consolidated Silver Standard Mines Ltd. in 1986. A total of 11 rock chip samples were collected from surface outcrop from an area of approximately 150 by 50 metres covering the southeast portion of the Snow zone, and a 300 by 50 metres area covering the northwest portion of the Rain zone.
Results from sampling in 2016 indicated that the Snow zone has relatively higher Si02 content(per cent SiO2/per cent Total = 99.56) than the Rain zone(per cent SiO2/per cent Total = 99.39) (Assessment Report 36446).