The Tidewater deposit is located on the north side of Alice Arm Inlet, about 3.0 kilometres east of Alice Arm. The deposit produced a limited amount of ore in 1916 and 1931 containing high grade molybdenite from quartz veins.
The mineralization in this deposit resulted from the intrusion of a small quartz monzonite stock into a sequence of argillite, siltstone, fine-grained sandstone, minor greywacke and tuff of the Middle Jurassic to Upper Cretaceous Bowser Lake Group. These rocks, striking west to northwest and dipping steeply to the north and south, have been metamorphosed to biotite hornfels from a few metres to 450 metres outward from the stock.
The stock is an irregularly shaped, 400 by 250 metre, northeast trending quartz feldspar porphyritic quartz monzonite intrusion typical of other Tertiary Alice Arm Plutonic Suite intrusions. The stock and veins are cut by northeast trending felsic and granodioritic dikes. Silicification, sericitization and argillic alteration occurs in the stock and along quartz vein margins.
High grade molybdenite mineralization is hosted in a system of quartz stringers, veins and lenses individually a few centimetres to 4.6 metres wide. The system, up to 20 metres wide, occurs on the southern contact of the stock and extends southwestward for a strike length of 280 metres, where it deteriorates into quartz stringers. The quartz veins and lenses strike northeast and dip steeply to the northwest. Molybdenite is irregularly distributed as 1 to 2 millimetre thick concordant bands or sheets and as disseminations, to a lesser extent, in the quartz, with minor pyrite. The pyrite content increases northward towards the stock.
Low grade mineralization occurs, more widespread, as thin bands and disseminations of molybdenite within a quartz vein stockwork in the stock, in adjacent hornfelsed sediments, in the stock itself and as coatings along fractures. Molybdenite occurs with pyrite and minor scheelite, galena and sphalerite. A sample assayed 0.0605 per cent molybdenum (0.101 per cent molybdenite) over 34 metres in hornfelsed sediments (Assessment Report 8589, page 6).
The deposit contains indicated reserves of 9,071,000 tonnes grading 0.06 per cent molybdenum (0.1 per cent molybdenite using a factor of 1.6681) based on drilling results (Property File - Richmark Resources Ltd., December 21, 1987).
The Tidewater deposit has recently been re-evaluated for gold and silver mineralization in polymetallic quartz veins and quartz breccias, not related to the quartz-molybdenite veins. These occur in the quartz monzonite stock and adjacent hornfelsed sediments associated with hematitic, argillic and sericitic alteration. Quartz veins, up to 4 centimetres wide, contain selvages and disseminations of molybdenite, pyrite, pyrrhotite and minor galena, sphalerite, tetrahedrite, chalcopyrite and ruby silver (pyrargyrite). Samples assayed between 0.31 to 0.96 gram per tonne gold and 269.4 to 884.1 grams per tonne silver over 0.61 to 0.91 metre (Assessment Report 17842, pages 9,10). Re-sampling of pulps and core from drilling in 1979 and 1980 resulted in gold assays of 3.55 grams per tonne over 2 metres from a fault zone and 7.90 grams per tonne over 2 metres in a sequence of carbonate veins in hornfelsed sediments adjacent to the stock (Richmark Resources Prospectus, 1987, page 6).
In 2005, New Cantech Ventures Inc. reported an option to acquire a 100 per cent interest in four mineral claims that cover the Tidewater occurrence.
The Tidewater deposit produced a limited quantity of ore in 1916 and 1931 from underground workings in the high grade quartz-molybdenite vein system. In 1916, 347.5 tonnes of ore was shipped with a reported grade of 0.959 per cent molybdenum (1.60 per cent molybdenite)(Bulletin 9, page 65). In addition, 40.8 tonnes of tailings were shipped that averaged 0.911 per cent molybdenum (1.52 per cent molybdenite)(Bulletin 9, page 65). In 1931, 1.22 tonnes of ore were shipped (Bulletin 9, page 66).
In 2017 an airborne magnetometer survey and geological interpretation were completed for Granby Gold Ltd. on their Tidewater property, north of Alice Arm. Alterations that are identifiable as related to the Tidewater intrusion are a zone of hornfels and an inner zone of molybdenite enrichment. The Tidewater stock is without readily discernable magnetic characteristics in an area of low remnant magnetism (Assessment Report 36830).
