The Midnight (L.1186) occurrence is located on the west side of Little Sheep Creek at an elevation of approximately 1067 metres and 1.6 kilometres west of Rossland.
Regionally, the area is underlain by mudstone, siltstone, shale and fine clastic sedimentary rocks of the Carboniferous to Permian Mount Roberts Formation; basaltic volcanic rocks of the Lower Jurassic Elise Formation (Rossland Group) and trachytic volcanic rocks of the Eocene Marron Formation (Penticton Group). The sediments and volcanics have been intruded by syenitic to monzonitic rocks of the Eocene Coryell Plutonic Suite to the west and quartz monzonitic rocks of the Early Jurassic Rossland Plutonic Suite and granitic rocks of the Middle Jurassic Trail Pluton to the east.
The Midnight veins lie within greenstone and altered greenstone of the Lower Jurassic Elise. These lie adjacent to the northern contact of a body of serpentinite, probably Permian, which trends east and probably dips steeply to the south. Many small shear zones along this contact suggest that it is an east-trending fault that is terminated by the Eocene Marron Group on the west and the Jumbo fault on the east.
The greenstone is very fine-grained, dense and massive rock of dark-green to brownish hue. The original texture has been destroyed by both the development of chlorite and fibrous amphibole and by local silicification and serpentinization. It varies from a highly altered rock with small amounts of serpentine and magnetite to a mottled phase and then a phase that carries abundant, uniform serpentinite and magnetite.
The typical massive serpentinite of the Permian ultramafic body is a very dense black rock with cross-fibre asbestos infilling joints as 0.2- to 0.6-centimetre veinlets, and light-green talc has developed in the immediate vicinity of the faults. In 1969, samples from underground workings near the northern contact of a mass of serpentinite on the Midnight property along the western side of Little Sheep Creek gave several thousand tonnes of serpentinite averaging 0.25 per cent nickel. Selected samples assayed up to 0.45 per cent nickel (Bulletin 74, page 23). The serpentinite hosts pyrite, millerite and a mineral of the linnaeite group. Chromite is associated with the fine-grained serpentinite.
The principal gold veinon the Midnight claim , referred to as the Baker vein, strikes north 020 degrees west and dips 65 degrees west in the Elise Formation volcanic rocks and serpentinite. The vein ranges in width from 5 centimetres to 1.5 metres and hosts free gold, pyrite, galena, chalcopyrite and sphalerite in quartz and ankeritic carbonate. The gold is present in very high grade pockets that are erratically distributed along the veins. Other individual veins are not a continuous body of quartz, rather, they are tight fractures that, every 15 metres or so, contain quartz lenses from 20 to 61 centimetres thick and 15 to 31 metres long that pinch and swell in both horizontal and vertical sections.
Other zones of gold mineralization are reported in local areas of pyrrhotite-pyrite–bearing, carbonate-talc-quartz–altered and carbonate-veined (Listwanite) serpentinized dunite that have been intruded by a north-trending lamprophyre dike swarm with pre- and post-mineralization dikes.
North of the mine workings, a quartz-feldspar intrusive and adjacent altered volcanics contain zones of garnet-epidote skarn hosting disseminated pyrrhotite with minor chalcopyrite, pyrite, arsenopyrite and scheelite. Magnetite and pyrrhotite with replacement veins are also reported in the altered volcanic.
In 1989, a drift through the serpentinite on the 3100 adit level was reported to cut a 15-metre wide mineralized zone grading up to 6.86 grams per tonne gold over its entire length with up to 17 grams per tonne gold over 4.6 metres (Vancouver Stockwatch, August 21, 1989, page 15).
In 1993, diamond drilling yielded up to 4.0 grams per tonne gold over 37.2 metres, including 29.1 grams per tonne gold over 3.45 metres and 15.4 grams per tonne gold over 6.3 metres, in hole 93-R-5 (Assessment Report 23857). Also at this time, underground sampling of the main Midnight adit and cross drifts yielded 19.4 grams per tonne gold over 4.5 metres of serpentine rock previously sampled in 1989, whereas channel samples from a short crosscut averaged 2.5 grams per tonne gold over 7.5 metres, including 3.5 grams per tonne gold over 1.5 metres (Assessment Report 23857).
In 1994, diamond drilling yielded intercepts of 1.0 gram per tonne gold over 44.7 metres, including three separate 1.5-metre intervals averaging 17.9, 8.4 and 7.9 grams per tonne gold, respectively, in hole MS-1; 1.4 grams per tonne gold over 7.2 metres in hole MS-2; 2.1 grams per tonne gold over 25.5 metres in hole MS-3; 26.4 grams per tonne gold over 3.45 metres in hole MS-5; 228.8 grams per tonne gold, 40.0 grams per tonne silver and 0.33 per cent copper over 0.15 metre in hole MS-7; 37.6 grams per tonne gold over 0.3 metre in hole MS-10 and 0.65 gram per tonne gold over 46.5 metres, with separate intervals yielding up to 4.2 grams per tonne gold over 2.55 metres in hole MS-12 (Assessment Report 23857). At this time an indicated reserve increase of approximately 18 144 tonnes grading 10.9 grams per tonne gold was reported (Assessment Report 23857).
In 1996, diamond drilling yielded intercepts of 63.5 and 10.2 grams per tonne gold over 12 and 15 centimetres, respectively, in hole 96-4 and 3.4 grams per tonne gold over 78 centimetres in hole 96-6 (Assessment Report 25007).
In 2015, a combined indicated mineral resource for the I.X.L. (MINFILE 082FSW116), O.K. (MINFILE 082FSW117) and Midnight (MINFILE 082FSW119) occurrences was reported at 48 000 tonnes grading 6.0 grams per tonne gold and 3.0 grams per tonne silver with an additional inferred mineral resource of 8000 tonnes grading 7.7 grams per tonne gold and 2.0 grams per tonne silver (Assessment Report 35609).
Between 1927 to 1974, 4760 tonnes of ore were mined resulting in the recovery of 218 346 grams gold, 124 383 grams silver, 2097 kilograms lead, 1460 kilograms zinc, and 62 kilograms copper. Former workings on the Midnight (L.1186) Crown grant include numerous adits and stopes, including the Midnight 3100 and 3200 adits and the Baker and No. 1 Vein stopes on the main area of workings and the Italian adit, located a short distance to the northeast.
The Midnight (L.1186) claim was Crown granted in 1897. No work was reported on the property until lessees began operations in 1925. The claim was owned by T.S. Gilmour in 1930. A small mill (7.3 tonnes per day) was installed on the property in 1932. Lessees continued to work the property until it was purchased by B.A. Lins in 1940. Lins carried out intermittent operations until Kootenay Central Mines Ltd. purchased the property in 1948. Small-scale operations were continued by the company or by lessees until 1952. Midnight Consolidated Mines Ltd. acquired the property in 1956.
A private company, headed by Messrs. Thompson and Sheward, began rehabilitation of the workings in 1964. In 1965, Cinola Mines Ltd. acquired an interest in the Midnight Crown grant (Lot 1186) and 12 adjacent recorded claims. The old workings were rehabilitated, short drifts and raises were driven and diamond drilling, totalling 610 metres on surface and 914 metres from underground, was carried out. In 1966, a new adit (3100 foot level) was begun 46 metres below the old workings and during 1967, approximately 305 metres of drifting and raising was done, including a raise to the old workings. Further drifting, raising and stoping was carried on in 1968 and a small amount of ore was shipped. Tull Mines Ltd., incorporated May 1968, agreed to participate in bringing the property to production. Construction of a 90 tonne-per-day mill was begun late in 1968 but was not completed under the agreement. In 1970, Federated Mining Corporation Ltd. optioned a 50 per cent interest in the property from Cinola Mines and mill construction was completed during that year. Some stope preparation and stoping was done to supply the mill with sufficient ore for recovery tests. Mill tune up operations reportedly began in June 1970, but subsequent modifications were required due to metallurgical problems. The mill operated briefly early in 1971; no production data has been released. All work at the property ceased in September 1971.
The company name was changed in January 1973 to Consolidated Cinola Mines Ltd. During 1973, approximately 200 tonnes of ore, mainly cleaned up from the idle mill on the property, was shipped to Trail. A November 1974 agreement between Consolidated Cinola Mines Ltd. and Sand Mines Ltd. called for the latter company to advance all necessary capital to put the property into production. Consolidated Cinola was to receive 20 per cent and Federated Mining 10 per cent of net smelter returns. Underground rehabilitation, development and diamond drilling began and small shipments of crude ore were made in 1975 and 1976.
Carnelian Mines Ltd. held the property in 1979 and reported a small shipment of crude ore. Tagus Resources Ltd. suboptioned the property from Carnelian in December 1979; the agreement was abandoned in 1980 following limited diamond drilling and sampling.
Drexore Developments Inc. optioned the property in 1987. In 1993 and 1994, Matovich Mining Industries Ltd. completed a program of geological mapping, a 15.0 line-kilometre ground magnetic survey and 16 diamond drill holes, totalling 2210.0 metres, on the area. In 1996, Minefinders Corp. Ltd., on the behalf of Matovich Mining Industries Ltd., completed a program of underground rehabilitation, mapping and sampling and seven diamond drill holes, totalling 877.8 metres, on the area.
During 2002 through 2004, Matovich Mining Industries Ltd. completed programs of underground development on the Midnight and I.X.L. claims. In 2005, West High Yield Resources Ltd. completed a program of geological mapping and a 11.2 line-kilometre ground magnetic survey on the area. In 2014 and 2015, ground self-potential and VLF-EM surveys were completed.
