Massive Sulphide ore breccia
Virtual Museum ID: 19-D17-07
siltstone breccia healed by (in sequential order) carbonate that rims fragments, sphalerite and chalcopyrite, and finally galena and arsenopyrite
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Original Collection:Smithers Exploration Group (SEG)
Sub Collection:Silver Standard
Virtual Museum ID:19-D17-07
Date Added to VM:2019-02-21
Sample Origin:North side of Mount Glen, B.C.
Specific Site:Silver Standard
Datum:09 (NAD 83)
VM Category:Ore Sample
Primary Features:Massive Sulphide ore breccia
Primary Mineral Formula:S^2-
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:Bowser Lake Group
Geological Period:Middle Jurassic to Lower Cretaceous
Stratigraphic Age:Late Cretaceous
Geological Terrane:Bowser Lake
Minfile ID:093M 049
The Silver Standard mine is located on the north side of Mount Glen, 8 kilometres northeast of Hazelton.
The Mount Glen area is underlain by a series of sediments, chiefly sandy, argillaceous and tuffaceous, belonging to the Middle Jurassic to Lower Cretaceous Bowser Lake Group. Cutting the sediments are small granitic bodies of the Eocene Babine Intrusions. Folding appears to have two main trends, which may be of different ages. The more conspicuous is a series of northeast trending folds whose axes are often only a hundred metres apart. There is also a broad, open, northwest trending anticline, 9 to 11 kilometres across, with its axis on Mount Glen, 1.6 kilometres northeast of the Silver Standard mine. The domal outline of the sediments on Mount Glen may be due to an intersection of these folds, or to an underlying intrusive. The known intrusive bodies show alignments parallel to the two trends.
The ore deposits of the Silver Standard mine are in a 243-metre thick stratigraphic section of the Bowser Lake Group. The section is composed predominantly of medium to fine-grained tuffaceous sandstones with minor beds of coarse-grained greywacke, and finer grained dark argillite. The tuffaceous sandstones are generally in beds from 0.3 to 2 metres thick and the argillite beds are 1 to 10 centimetres thick. The overlying rocks contain more greywacke and argillite and lesser tuff, with some evidence of plant remains. In the underlying strata the rocks are mainly argillite and greywacke. Parallel to the folding on the southwest, outcrops of quartz porphyry indicate an elongated intrusive body approximately 487 by 91 metres. The mine drifts and drill holes have only intersected northeast trending dikes of this porphyry.
The largest fold in the vicinity of the mine is the northwest striking dome or anticline. Since its axis lies to the northeast, the general dip of the beds in the mine area is southwest at low to moderate angles. A smaller, sharper anticline trending 005 degrees cuts through the mine above the number 7 vein. Cutting across the productive sections of the numbers 4 to 8 veins is a gentle anticline or monocline striking 300 degrees; this is parallel to the major dome and to the quartz porphyry body.
A fault zone striking north and dipping 40 degrees west has been traced for 609 metres in the mine area. The fault zone is up to 15 metres wide and consists of a series of fault planes. It is a post- vein structure and has a normal dip movement of approximately 76 metres. A complimentary set of small normal faults, striking north and dipping steeply east, offset number 7 and 8 veins. They are post-vein structure but pre-ore.
Quartz veins occupy northeast trending faults or fissures. A series of parallel veins, striking northeast and dipping southeast, are numbered from 0 to 12, starting in the northwest. They lie within a zone trending 110 degrees. The distance between the number 0 and 12 veins is approximately 1600 metres. Their dips range from 35 to 80 degrees but are generally 60 to 70 degrees. The vein walls are commonly free, with gouge or ribboned rock on their margins. There has been minor movement before, during and after mineraliza- tion; slickensides and offsets of bedding indicate both horizontal and downdip displacements. In the central part of the mine area there is very little offset of the ore shoots by cross faulting, though number 1, 7 and 8 veins are displaced up to 6 metres by an east dipping normal fault. Several cross-veins, dipping northeast, have been found between the number 8 and 12 veins. The productive veins are near the centre of a domed area on the west limb of the anticline and are nearly normal to the attitude of the beds. No major veins have been found on the east limb of the anticline.
The veins consist mainly of milky white quartz that is generally massive and fractured, massive white calcite and buff siderite. Vein widths vary from a centimetre to as much as 3.6 metres, but average 0.3 to 0.9 metres wide. Splits in the veins are common. The average width of the ore shoots range from 0.3 to 0.6 metres. Sulphide minerals present in the veins in approximate order of abundance are: sphalerite, pyrite, arsenopyrite, galena, pyrrhotite, tetrahedrite and chalcopyrite. A minor amount of a lead bismuth mineral, probably cosalite, occurs in vein 8, and a small particle of pyrargyrite was reported in vein 7; scheelite is present in the number 1 vein. Some jamesonite and freibergite have also been reported in the veins. The sulphides are as a rule, massive and occur in pockets and irregular veinlets which tend to be parallel to the vein walls, and are either near one wall of the vein or where the quartz is fractured. The veins contain many wallrock inclusions, some of which are irregular and angular and others, thin slabs oriented parallel to the vein walls. Generally, the inclusions are within 0.6 metre of the veins and are partly replaced by pyrite and arsenopyrite.
In all the veins, except number 6 vein, the known ore shoots extend within 60 to 152 metres of the surface. The larger number 6 vein is mineralized to 304 metres below the surface.
Each vein is enclosed in an alteration zone in which the tuffaceous sandstone is bleached from an original grey colour to a light cream or tan due to the introduction of ankeritic carbonate, silica and possibly feldspar. Beyond these zones the rock becomes greenish and calcareous, forming an outer halo impregnated with calcite and chlorite.
Past work included extensive underground development. Historic production from number 1, 4, 6, and 7 veins provided most of the ore. More than sixty per cent of the production was from the number 6 vein which had an ore shoot 182 metres long and extended 304 metres downdip.
The showings were staked in 1910 by Messrs. Long and McBain who developed them for a short time. The Silver Standard and Canadian King groups of 6 claims each were acquired in 1911 by the Stewart, McHugh, and McLeod syndicate on a lease with option to purchase. In 1913 a total of 14 claims (Lots 2409-2415, 2417, 2259-2264) were Crown-granted to the syndicate. Steady development work was carried on except for a period between 1914 and 1915 when the mine was closed due to war conditions. A 50 ton (45 tonnes) mill of the water concentrator type was completed in May 1918 and operated intermittently until October 1920, and for about 3 months in 1922.
The syndicate formed Silver Standard Mining Company Limited in April 1937, this being a private company largely owned by Major General J.W. Stewart. The mine remained inactive until Nay 1938 when rehabilitation of the workings was begun by Canadian Cadillac Gold Mines Limited; operations were suspended early in 1939 due to lack of funds. Omineca Base Metals, Limited, held the property in 1943 but no development work was reported at that time.
No further activity was reported until Silver Standard Mines Limited was organized (December 1946) to acquire from the Silver Standard Mining Company Limited the 14 Crown-granted claims and 24 claims held by location. Exploration and development work was begun and a 60 to 75 ton (54 to 68 tonnes) per day flotation mill was built and put into operation in September 1948. The mine was developed by two crosscut adits driven southeastward on the 1500 and 1300 levels, and by a 155-metre vertical shaft from the 1300 level with cross-cuts on the 1150, 1000, and 850 levels. A biogeochemical survey in 1953 located several anomalies but no ore shoots were found by subsequent exploration work. A geophysical (resistivity) survey was carried out over approximately 470 acres, extending in all directions beyond the mine workings and beyond any previous surface stripping. A large number of anomalies were found which on investigations were found to include minor veins, known shears, shears containing pyrite, and beds of argillite; no new orebodies were found. Approximately 3000 metres of bulldozer stripping was done in 1955. Half of this was in a single trench the same distance south of the intrusions as the major ore shoots are north; nothing of importance was found.
All underground work by the company ceased in May 1958 with the completion of mining on the No. 11 and No. 10 cross-veins. All known ore shoots had been mined and considerable underground exploration and development work was done in an effort to find additional reserves. Lessees mined and shipped small remnants of high grade ore during the period 1959-1965.
National Exploration, Limited, in 1950 acquired 60 recorded claims, lying below the 1500 foot elevation, some southwest and others northeast of the Silver Standard property. Geophysical surveys located 2 anomalies, one on each claim group. Diamond drilling of the anomalies in 1951 located some quartz veins but no intersections contained economic mineralization.
The Silver Standard claims were leased by Northwestern Midland Development Co. Ltd. and mining of remnants of faulted ore sections was begun in 1967. In 1968 a total of 17 metres of drifting was done on No. 2 and No. 10 veins. 182 tonnes of selected high-grade ore was shipped and 508 tonnes was mined and milled. Work during 1969 included 26 metres of subdrifting on No. 10 vein, and 64 metres of diamond drilling in 6 holes. Nine hundred and fifty-two tonnes of ore were mined and 802 tonnes milled.
In 1974, George Braun was able to negotiate a long-term lease with Silver Standard Mines Limited. For the next 15 years he was able to earn a living in small-scale mining, shipping hand-sorted ore to the smelter at Trail. Due to low metal prices and escalating costs Mr. Braun was forced to cease operations in 1989.
From 1913 to 1922 and from 1948-1989 (excluding 1961, 1964, 1966, 1972, 1980, 1986, 1987) a total of 205,056 tonnes were mined from which 237,387,811 grams of silver,464,632 grams of gold, 12,283,325 kilograms of zinc 7,957,686 kilograms of lead, 202,650 kilograms of copper and 146,767 kilograms of cadmium were recovered.
In 2008, these claims came open and were staked by George Braun. In 2009 the author ran a VLF-EM survey on the area south of the intrusions to determine if the known veins might extend beyond the intrusions, and to explore the possibility of finding a mineralized belt in this area similar to the one on the north side (Assessment Report 30854). The VLF-EM survey was successful in defining a series of north-south trending anomalies which seem to correlate with the projections of known veins to the north of this area. In the course of running this survey, the author found evidence of quartz veins.