Magnesite forms a bed which is conformably interbedded with quartzites of the Lower Cambrian Cranbrook Formation, about 7 kilometres south of the town of Marysville. The area is underlain by a sequence of thinly banded, reddish quartzitic and buff-coloured magnesite beds and is overlain by magnesite interstratified with thin, greenish argillite beds and locally thin limestone. The magnesite varies from coarse to finely crystallin, weathering to a rough and commonly rusty brown exterior. The magnesite member of the Cranbrook Formation quartzite is extensive throughout the local area as lenses along a 6-kilometer strike length. In the southern portion of the Marysville magnesite there appears to be north-northeast trending, steeply west dipping layer approximately 1000 meters in strike length, and in the range of 3-15 meters width. Fresh surfaces are pearly grey, white or cream-coloured and are cut by minor quartz veins or host to knots of quartz. The best bed of magnesite is about 15 metres thick, and samples indicate the following chemistry: 4.54 per cent SiO2, 2.4 per cent Fe2O3, 0.4 per cent Al2O3, 0.79 per cent CaO, 43.7 per cent MgO, and 48 per cent Loss on Ignition (PFD 3446).

Minor production has been reported for the Marysville deposit (Z.D. Hora, personal communication, 1990), but no figures are available.

WORK HISTORY

In 1932 the Geological Survey of Canada announced the discovery of coarse crystalline magnesite in the area between Perry Creek and St Mary River. Cominco acquired the property and conducted subsequent mapping and sampling, including a 2,700-tonne bulk sample shipped to Trail, BC in 1931 (EMPR FICHE). In 1937 Comino mined a test sample of 21.3 tonnes. Cominco held the mineral title for Marysville magnesite for several decades and did not file any assessment reports so there are no public access documents for work done by Cominco on the property. The Consolidated Mining and Smelting Company of Canada Limited acquired 16 Crown Grants over the property in 1937 and 1938.

A map published in the Minister of Mines Annual Report for 1964 (page 187) suggests that Cominco performed considerable stripping and trenching at the north end of the magnesite zone, at an elevation of 4,060 to 4,120 feet (1,237.5 to 1,255.8 metres) for a length of about 500 feet (152.4 metres) across widths of 50-60 feet (15.24-18.3 metres). The main excavation where Cominco removed 2,700 tonnes came from a northeast trending pit that is about 49 metres long and 15 metres wide. A total of 4 diamond drill holes appears to have been drilled 50-150 meters west of the trenches. Cominco did not pursue commercial production and the claims eventually lapsed.

In 2000, the Marysville magnesite property was acquired by Magna Precious and Industrial Minerals Inc the property was optioned to Stralak Res Inc. It was announced that the main purpose of the property acquisition was to produce magnesium chloride, considered to be suitable for the replacement of road salt with magnesium chloride. Stralak Res did not file any assessment work.

In 2007, D Fredlund performed prospecting on 125 hectares and filed an assessment report (Assessment Report 30075). One sample was reported taken from the north portion of the claims and was analyzed by ALS Minerals and returned values of 41.9 per cent MgO, 7.39 per cent Si02, 0.39 per cent Al2O3, 1.48 per cent Fe2O3, and 0.36 per cent CaO. The claims were allowed to lapse and MGX Minerals Inc acquired the south portion of the Marysville magnesite zone.

In 2013, Wallace Neale collected 3 magnesite samples on his tenures over the Marysville occurrence (Assessment Report 34831).

In March 2015, MGX Minerals Inc performed sampling (6 samples) and mapping in the north and central area of the property (Assessment Report 35436). A further 10 samples were collected in late June of 2015. Results from the 2015 rock chip samples are given in the assessment report for that year. In 2016, MGX carried out geochemical sampling and geological mapping on the north portion of Marysville magnesite (Assessment Report 36600). In 2017, MGX carried out geochemical rock sampling of the South Zone (near Antwerp Creek canyon) (Assessment Report 36596). Sample locations and whole rock geochemical analysis of rock chips from magnesite outcrop and float are provided in the assessment report for that year. In 2018, MGX Minerals Inc performed geochemical sampling on the south portion of Marysville Central Magnesite Zone. Geological descriptions and geochemical analysis results are provided in the 2018 assessment Report (Assessment Report 37598). In 2019, MGX collected a total of 10 rock chip samples each taken over a 2-meter interval of sparry magnesite from various surface outcrops (Assessment Report 38602). Work in 2019 focused on north extension of the Central Zone. Assessment work in 2022 by MGX included collection of 12 rock chip samples (Assessment Report 40393).