The Mica Mountain (Bonanza) occurrence is located on the northern flanks of Mica Mountain between approximately 2072 and 2487 metres elevation. Tete Jaune Cache is approximately 10 kilometres to the northeast.
Regionally, the area is situated near the eastern edge of the Cariboo-Cassiar terrane on the western side of the Rocky Mountain Trench and is underlain by coarse clastic sedimentary rocks of the Neoproterozoic Kaza Group and fine clastic sedimentary rocks (mudstone, siltstone, shale) of the Neoproterozoic Kaza Group, Lower Division. To the south-southeast the sedimentary units have been intruded by a small body of Early Carboniferous foliated granitic to dioritic rocks.
Locally, mica is hosted in pegmatite dikes and sills. Sills are transposed and deformed with host lithologies, whereas dikes crosscut foliation and folds of hostrocks. Based on crosscutting relations, pegmatite bodies were intruded prior to and after phase three deformation. Phase three deformation consists of variable developed crenulation cleavages on a microscopic and mesoscopic scale and open to tight, isoclinal folds (coaxial with phase two folds) on a mesoscopic and megascopic scale. These later pegmatites have small apophyses into host lithologies, which show no evidence of strain. Pegmatites are hosted in pelitic schists of the Neoproterozoic Kaza Group, Lower Division. Schists are largely mica-garnet, quartz-mica and quartz-feldspar-mica in composition. Other lithologies of the Neoproterozoic Kaza Group, Lower Division include psammite, amphibolite, marble and calc-silicate. The Canoe South Mica showing (MINFILE 083D 017) contains a more detailed description of the regional deformation and conditions of metamorphism in the area. The age of pegmatites has been determined as 154±6 Ma and 125±7 Ma for pre- and post-phase three deformation pegmatites, respectively.
Quartz, feldspar and muscovite comprise the main constituents of the pegmatites. Accessories include garnet, tourmaline, kyanite, beryl and apatite. Pegmatites are commonly irregular and lens-like bodies, most frequently oriented 135 degrees and dipping 30 to 40 degrees to the southwest. Textures within these bodies vary greatly with only certain mica bands large enough to be of commercial value (Minister of Mines Annual Report 1920). Where muscovite is of good quality, it is light brown to light greenish and occurs in well-formed booklets ranging from 10 by 10 by 1.25 centimetres to 45 by 30 by 5 centimetres; however, the quantity in any one pegmatite is not unusually high (Geological Survey of Canada Economic Geology Report No. 19). In certain pegmatites, muscovite was noted to be the best quality and of the greatest abundance in small pockets near the hangingwall (Minister of Mines Annual Reports 1899, 1913). Elsewhere, quality muscovite was observed concentrated in bands up to 1.5 metres wide on either side of the hanging- or footwalls (Assessment Report 276).
Beryl was reported in pegmatite on the Bonanza property on Mica Mountain by McEvoy (Minister of Mines Annual Report 1898) and deScmid (Minister of Mines Annual Report 1913). Lay (Minister of Mines Annual Report 1928) found no trace of beryl or any other unusual accessory mineral. A composite sample was reported to contain less than 0.01 per cent beryllium (GSC spectrographic analysis; Geological Survey of Canada, Economic Geology Report No. 23).
Work History
Mica Mountain has a long history of mica and lesser kyanite prospecting and exploration recorded as far back as 1893 with the staking of Lots 510 through 516. At various times attempts have been made to develop properties on Mica Mountain, but the showings contained too low a proportion of sheet mica of marketable grade to permit profitable operation at this time (Minister of Mines Annual Report 1947). Work on these claims consisted primarily of short adits, winzes and trenches along and into pegmatite bodies. Adits are reported on the Mica claim, located northeast of the Dreadnot L.514 Crown-granted claim, at an elevation of approximately 2307 metres and approximately 1.3 kilometres to the south on the Bonanza L.516 Crown-granted claim at an elevation of approximately 2393 metres. Most of the historical production is reported to have been from the Bonanza L.516 Crown-granted claim.
In 1940, the historical occurrences were staked by Groves as the Mica claim and following year a program of prospecting and geological mapping was conducted. In 1958, a program of geological mapping was completed on the area as the Barron claims by J.F.V. Millar.
In 2023, VanderWart Consulting Inc. conducted a minor program of prospecting and geochemical (rock and silt) sampling on the area as the Mica Mountain property. Samples were tested for rare earth elements but yielded generally low values with a maximum of approximately 0.092 per cent rare earth elements from silt sample 74833 (Assessment Report 41700).
