Oxidized Au ore
Virtual Museum ID: 19_GM08
Gold is a valuable, highly prized mineral used in everything from jewellery to electronics and dentistry. Gold is desirable due to its special properties, such as malleability and resistance to tarnishing. Gold is commonly microscopic or embedded within or around sulphide grains. Free visible gold occurs as disseminated grains, or rarely as crystals. Crystals of gold commonly form within or around quartz. In its natural mineral form, gold is commonly alloyed with silver. Gold is distinguishable by its characteristic golden yellow colour and extreme heaviness.
The information listed below relates to the current holding location or collection that the sample is from, and whether the item is viewable at that location or is part of a private collection. Coordinates are given as guides, and we remind you that collecting specimens from these locations is not allowed. Caution is advised visiting such sites and Below BC assumes no responsibility for any injuries or trespassing charges that may occur as a result of the viewer entering these sites.
Original Collection:Greenwood Museum (GM)
Virtual Museum ID:19_GM08
Date Added to VM:2019-06-06
Sample Origin:Providence Lake, British Columbia
Specific Site:Sylvester K Mine
Datum:11 (NAD 83)
VM Category:Ore Sample
Primary Features:Oxidized Au ore
Primary Mineral Formula:Au
Primary Category:native element
Advanced Geological Information
The following section provides geological data relating to the specimen or the site it was collected from, when available. Information has been obtained from various sources including private and government datasets but may not be up to date. Any geological time periods or ages listed often relate to the primary geology of the area, and may not be the actual date of an event such as mineral formation.
Geological Formation:Brooklyn Group
Stratigraphic Age:201.3 to 252.17 Million Years
The Marshall (Lot 2388) and adjoining Sylvester K (Lot 2382) claim (082ESE046) claim are centred near Providence Lake, 1.7 kilometres northwest of Phoenix and 5.8 kilometres northeast of Greenwood. Access is via the Providence Lake road which runs north from the Phoenix mine site.
Between 1967 to 1975, 370 tonnes of ore was shipped from the Marshall claim, yielding 15.2 kilograms of gold, 17.6 kilograms of silver, 0.47 tonne of copper, 2.3 tonnes of lead, and 0.56 tonne of zinc.
The Marshall claim was Crown granted in 1904. Several hand dug trenches and two shafts near the west boundary of the claim are the only remnants from the early years of prospecting. The first major exploration activity was undertaken in 1938 when seven holes comprising 411 metres of diamond drilling and much bulldozer trenching was completed between the two old shafts. The first shipment of ore was in 1967 by leasees from an open cut on the 'San Jucinto zone', 120 metres west of Providence Lake. In 1968 this zone was explored further by 560 metres of diamond drilling and bulldozer trenching. This eventually resulted in the ore shipments. Bulk sample work in 1974 by San Jacinto Explorations Limited, indicated a resource of 45,350 tonne at 17 grams per tonne gold (Northern Miner, October 25, 1979).
The principal rocks underlying the Sylvester K and Marshall claims are sedimentary units of the Triassic Brooklyn Group and offshoot apophyses and dikes of the Lower Jurassic Providence Lake microdiorite stock. The Brooklyn beds are steep, mostly easterly dipping, comprising thick basal sharpstone conglomerates, overlain by a relatively thin transitional argillaceous facies, and a thick upper limestone unit. The Providence Lake microdiorite stock, dated 206 Ma, intrudes the limestone and conglomerate, feeding the somewhat younger volcanic rocks of the Eholt Formation.
Mineralization comprises stratabound massive sulphide in limestone lenses and sulphide disseminations in the accompanying sharpstones and argillaceous rocks of the Brooklyn sequence. The ore mineralogy consists principally of pyrite and smaller amounts of pyrrhotite and marcasite, and traces of chalcopyrite accompanied by carbonates, quartz, and chlorite. The San Jacinto zone has a somewhat broader array of minerals that includes magnetite, specularite, galena, sphalerite, garnet, epidote, and amphibole. The effect of the mineralizing solutions on wallrocks of the ore zone is well displayed in the Sylvester K zone where the footwall argillites have been transformed locally into a fine grained biotite bearing hornfels. Here numerous thin pyrite stringers carry gold and silver values for more than 10 metres distal from the massive sulphide bodies. Elsewhere, chlorite and hematite are common on joints and cracks in the host rocks.
Source of the mineralizing solutions is believed to be the microdiorite stock, although no significant mineralization is visible south of Providence Lake where the main microdiorite body intrudes the Brooklyn limestone. However, considering the wide distribution of microdiorite dikes in the area, it is possible that the principal plutonic body lies at depth.