Silver Zinc Lead +/- Au ANDX w/ Vn1
Virtual Museum ID: 19-BCGS-BKR1
Silver is an important precious metal. It is still highly valued today and has many important uses, as well as being used for jewellery. Silver has the highest electrical and thermal conductivity and reflectivity of all metals and is widely used in electronics and industrial chemistry. It is also used to make mirrors, photographic and x-ray film and collectible coins. Silver has natural antiseptic properties, therefore, has many different medical applications. Silver can occur in its elemental form as metallic silver, or in compounds and minerals with other elements like gold and lead. Silver has a distinct silver-grey colour and is soft and malleable, meaning it can be easily worked and shaped.
Sphalerite is the main ore mineral for zinc, and although relatively common, finding it in commercial amounts is somewhat rarer. The zinc will give the mineral a yellow or red hue, but iron can replace the zinc in the atomic structure, making the crystals black. Rarely, cobalt finds its way into the structure, and produces green crystals. Although sphalerite is a relatively soft mineral, it can be cut (faceted) into attractive gems, which are used for mineral displays.
Galena is the main ore mineral for lead. Because of its relatively low melting temperature it can be easily smelted and has been used as a source of lead since ancient times. Galena has a cubic crystal system and can often be found as cubes or octahedra. Its shiny grey metallic lustre and heavy, dense nature make it easy to recognize. Galena often contains small amounts of silver, which add to its economic value.
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:British Columbia Geological Survey (BCGS)
Virtual Museum ID:19-BCGS-BKR1
Date Added to VM:2019-05-07
Sample Origin:Peace River, B.C.
Specific Site:Baker Mine
Datum:09 (NAD 83)
VM Category:Ore Sample
Primary Features:Silver Zinc Lead +/- Au ANDX w/ Vn1
Primary Mineral Formula:Ag · Zn · Pb · 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:Takla (Stuhini) Group
Geological Period:Upper Triassic
Stratigraphic Age:235 - 201.3 Ma
Minfile ID:094E 026
A small window of Upper Triassic Takla (Stuhini) Group volcanic rocks are intruded by granitic stocks of the Early Jurassic Black Lake Suite and overlain unconformably by Jurassic and younger volcanic and sedimentary rocks. The oldest rocks in the area are occasional wedges of crystalline limestone, up to 150 metres or more thick, which are part of the Permian Asitka Group. To the north and east, the Takla Group rocks are unconformably overlain by gently dipping porphyritic flows and fragmental rocks of the Lower Jurassic Toodoggone Formation (Hazelton Group). To the west, the Toodoggone volcanics are unconformably overlain by Upper Cretaceous-Eocene (?) Sustut Group sedimentary rocks. The rocks in the area have been subjected to extensive normal block faulting from Jurassic to Tertiary time, and by thrusting of the Asitka Group rocks over the Takla Group rocks during the Middle Jurassic.
Four principal rock units of the Takla Group underlie the Baker property: augite porphyritic andesite, fine-grained andesite, pyroclastic breccia and feldspar porphyritic andesite. A dacite unit has been recognized and is approximately 10 to 20 metres thick. The oldest and most prevalent unit is the augite porphyritic andesite. With the exception of the dacite unit, the Takla Group rocks are all epidotized. The augite porphyritic andesite, fine-grained andesite and dacite are commonly silicified, particularly in the vicinity of quartz veins. A thrust faulted block of calcite marble of the Asitka Group occurs immediately to the west of the gold-silver bearing A vein. The block is inferred to have a minimum thickness of 150 metres. Limited observations indicate that the volcanic units strike north in the southwest, and northeast in the east, with steep to moderate dips. As exposed, the sequence appears to represent part of a northeast striking and southwest-plunging anticline.
The Takla Group rocks are intruded by granitic stocks of the Black Lake Suite, the largest of these, the Black Lake stock, extends 9 kilometres southeast from the Baker property. Its composition varies from granodiorite to quartz monzonite. Radiometric potassium-argon dates obtained by the Geological Survey of Canada on hornblende from this pluton indicate an emplacement age of 186 Ma. Another pair yielded ages of 189 Ma and 200 Ma on biotite and hornblende respectively (Property File - Barr, 1978). Two small syenomonzonite intrusions occur immediately to the north of the Black Lake stock near the A vein. Highly altered quartz feldspar porphyry which appears to be a late phase of the syenomonzonite intrusions, occurs immediately to the north of the A vein. The main portion of this porphyry unit lies at the fault contact between Asitka Group and Takla Group rocks near the western end of the A vein. Dike-like apophyses of this body, varying from 1 to 30 metres in thickness, subparallel and intersect the northeast extension of the A vein.
At the Baker mine property, seven quartz vein systems occur, cutting Takla Group rocks; two have been mined. The veins are the A, B, C, D, North Quartz, West Chappelle and North Black Gossan and occur within an area of 2500 metres. They occur within an uplifted block of brightly iron-stained basalt and andesite flows of the Takla Group. The veins occupy two principal trends: northeast and east-southeast. Wallrocks are variably silicified and altered to sericite, clay minerals and carbonate with intensity increasing with proximity to vein structures.
The main production at the Baker mine was from the A vein, a fault-controlled quartz vein system composed of two or more subparallel veins which strike northeast and dip from 80 degrees southeast to approximately 70 degrees northwest. The quartz vein system has been traced for a strike length of 435 metres and across a width varying from 10 to 70 metres. Individual veins within the system vary from 0.5 to 10 metres in width. Drilling indicates that the vein system persists for at least 150 metres vertically from surface. The A vein is the most southeasterly of the two principal veins in the system and, where both veins have been intersected in drillholes, they generally lie about 15 metres apart. Throughout most of its length, the A vein lies within altered Takla Group augite porphyritic andesite and dacite, which are intensely silicified on vein walls. At intervals, it lies partly along a contact between quartz feldspar porphyry on the northwest and Takla Group volcanic rocks on the southeast. Near it southwest limit, a lobe of quartz feldspar porphyry extends northwest along the contact between a small stock of syenomonzonite and wedge of Asitka Group marble.
The A vein system is cut by numerous crossfaults which offset portions of individual veins, commonly for 1 to 15 metres and in one instance, for an inferred plan offset of 30 metres in a small graben structure. Most of the faults are northwest striking normal and reverse faults dipping to the northeast, and dip-slip strike faults dipping at shallow angles, generally to the southeast. Wallrocks, particularly in the hangingwall, are badly broken. The quartz vein is broken into segments less than 30 metres in length.
A variety of quartz vein textures and crosscutting relationships indicate a complex history of veining with multiple depositional stages. Much of the quartz is massive and drusy, whereas a distinctive earlier ribboned variety is common, particularly near vein contacts. The quartz varies in colour from white to grey to dark grey.
Gold-silver values are generally associated with highly fractured and occasionally brecciated white to grey, vuggy quartz veins containing 1 to 10 per cent pyrite, and to a lesser extent occur in silicified wallrock. Xenoliths of altered andesite and dacite frequently occur in the veins. The only other common gangue mineral is carbonate, which fills fractures.
Higher grade mineralization is associated with grey quartz, which occasionally contains visible argentite, commonly associated with disseminated grains of pyrite, chalcopyrite and very minor sphalerite. High grade gold-silver values occasionally occur in narrow (1 to 5 centimetres) crosscutting silicified shears. Visible gold is rare. Significant precious metals were found to be contained in a flat-lying shoot 200 metres in length by 3 metres wide and extending to a depth of 40 metres below surface.
Polished section, x-ray diffraction, and electron microprobe studies indicate that pyrite is the dominant mineral, constituting about 90 per cent of sulphide mineralization. It occurs as euhedral grains and includes blebs of chalcopyrite, electrum, argentite, bornite and sphalerite. Sphalerite constitutes about 3 per cent of the sulphides and is commonly enclosed in pyrite. Argentite is commonly interstitial between pyrite, chalcopyrite and gold. Electrum is frequently associated with argentite. The form of occurrence of gold is similar to that of argentite and electrum. Bornite occurs as blebs in pyrite or with chalcopyrite. Galena occurs as rare discrete disseminated grains. Chalcocite forms thick coatings on chalcopyrite and covellite forms a thin coating on both chalcocite and chalcopyrite in the oxidized part of the A vein. Polybasite and stromeyerite are rare constituents.
Surface oxidation in the A vein area extends to a depth of 5 metres or more below surface and is reflected by the presence of hematite, jarosite and goethite as pyrite alteration products in vugs and fractures, particularly near surface.
A production decision was made in 1979 to mine the A vein system and the Baker mine went on stream in May, 1981 with operations continuing until Nov. 30, 1983. DuPont of Canada Exploration Ltd. was the operator. Remaining unclassified reserves are 9070 tonnes grading 8.47 grams per tonne gold and 159.4 grams per tonne silver (Open File 1992-1).
The B (Multinational B) zone or B vein system is 365 metres northeast of, and on strike with the A vein. The B zone is similar in style and structure to the A vein and has been traced over a northeast strike length of more than 250 metres and to a depth of nearly 200 metres. Drilling has defined a vertically to steeply northwest dipping quartz (carbonate) vein structure that strikes 055 degrees. True widths of the structure vary from 2.4 to 7.6 metres. B zone reserves are 45,355 tonnes, grading 19.53 grams per tonne gold and 176.88 grams per tonne silver (George Cross News Letter No. 213 (November 4), 1988). Gold and silver are contained within a steeply northeast- plunging shoot within the plane of the vein. The surface expression of the B zone is a network of narrow quartz veins and veinlets having an overall east-southeast strike with moderate northeast dips. These are interpreted as being part of the hangingwall alteration zone which also features moderate to intense quartz-carbonate-sericite- clay minerals alteration of the volcanic hostrocks. Precious metal values within the alteration zone are low. Takla Group rocks at the B zone comprise augite porphyritic andesite, the most prevalent unit. Dacite, in part an alteration of andesite, but also a discrete unit, is variably silicified. Intravolcanic sediments, in the form of banded siltstones occur within the sequence. All rocks contain disseminated pyrite and are variably altered, epidote being prominent within the andesitic unit. Dacites within the hangingwall alteration zone are transformed to a creamy white rock featuring abundant sericite, carbonate and clay mineral alteration with numerous quartz veinlets and disseminated pyrite. Limy siltstones locally feature skarn alteration in the form of garnet, epidote and considerable pyrite.
Takla Group rocks are intruded by coarse-grained quartz feldspar porphyry and equigranular finer grained pink felsic units. A quartz feldspar porphyry dike apparently marks the southwest limits of the B zone. The intrusive rocks contain some quartz veins.
Structural complexity of the B zone is in the form of fault offsets which increases with depth and along strike to the northeast. Vein contacts are commonly marked by gouge zones.
At least three stages of quartz veining are evident within the B zone structure. Earliest stages include a drusy grey variety with small carbonate patches which is commonly fractured and brecciated and healed by a creamy white chalcedonic quartz and by later quartz-carbonate stringers. Pyrite is a common constituent and chalcopyrite is a good indicator of gold mineralization - better gold grades have a direct correlation with copper values. Galena and sphalerite are also common vein constituents but are more prevalent in gently dipping vein structures in the hangingwall.
The North Quartz zone is 1050 metres northeast of the A vein and consists of steeply dipping quartz veins with west-northwest strikes exposed over an area of 100 by 300 metres at the head of a cirque. Drilling in 1987 intersected narrow (less than 1 metre) quartz veins containing disseminated pyrite, galena and sphalerite.
Both C and D veins are partly exposed on steep mountain slopes. The C vein is located 750 metres northwest of A vein, and D vein is 650 metres north-northeast of A vein. Chip samples from C vein assayed up to 1.3 grams per tonne gold and 27 grams per tonne silver across a width of 1.6 metres. The D vein is essentially barren of precious metal content (Property File - Barr, 1978).
At the West Chappelle vein system, 1400 metres west-southwest of the A vein, a shallow drillhole assayed 1.3 grams per tonne gold and 16.8 grams per tonne silver over a core length of 1.2 metres (Property File - Barr, 1978).
Sampling of a narrow quartz vein at the North Black Gossan area yielded low gold-silver values.
To mid-December 1991, Sable Resources had mined approximately 9978 tonnes of material of greater than 17 grams per tonne gold from the B zone deposit area but was forced to cease operations in November 1991 due to poor underground conditions (T. Schroeter, personal communication, 1992). This ore is included with the Shasta Production.
Ore from the Shasta mine (094E 050) was transported to the Baker mill for processing.
The Chappelle property was acquired by Multinational Resources Inc. from DuPont in 1985 and over the next 3 years extensive exploration by Multinational was carried out on the Vein B deposit. In 1991, Sable arranged with Multinational to mine and mill the Vein B and did so to 1997. The operation was initially by underground methods of mining and reverted to surface and open pit methods due to the very unstable ground conditions. Although much of the exploration between 1985 and 1988 on the Chappelle property focused on the immediate area of the Vein B deposit, several surveys were carried out on the peripheral mineral claims and in 1989 Multinational carried out an extensive exploration program consisting of 15 kilometers of VLF-magnetic geophysics, trenching and the analysis of 653 soil and 3 16 rock samples. The 1989 program was successful in discovering seven new areas of gold mineralization, which warranted drill testing of the target areas. These targets areas were the B Vein Offset, West Cirque zone, Peter's Gulch Showing, Price zone, Northwest zone, Mt. Shasta Area and Clancey-North Black Gossan zone. In 1996, Sable acquired the Chappelle property by the acquisition of Multinational Mining Inc., a private company, now a wholly owned subsidiary of Sable.
Sable Resources planned to develop (1996) a small open pit on the Multinational B zone (B vein). They processed approximately 2267 tonnes of ore this year, but were unable to complete their program due to early onset of winter. The company plans to spend a minimum of $150,000 on exploration next year and an additional $100,000 on reclamation (B. Lane, personal communication, 1996). The company states that approximately 725 to 907 tonnes of ore grading 34.2 grams per tonne gold equivalent is 'available' for extraction from the B vein open pit. In 1996, Sable produced 52,720 grams of gold, 507,267 grams of silver and 8600 kilograms of copper from 2337 tonnes of ore from underground mining on the B vein. In 1997, the company milled about 1600 tonnes of ore from the B vein open pit and re-processed about 545 tonnes of tailings, yielding 35,085 grams of gold, 220,337 grams of silver and 4476 kilograms of copper (Information Circular 1998-1, page 22 and T. Schroeter). This ore has been mined out via a surface cut and re-processing of old mill tailings (T. Schroeter, personal communication, 1997).
Sable Resources drilled 10 holes in 1998 and explored in 1999. New discoveries include the Ridge zone, located northeast of the mined out A vein, and Beck vein. The Beck vein is 1.5 metres wide and has been exposed for about 30 metres. It appears to be associated with altered quartz feldspar porphyry generally believed to be the source of vein A. The Ridge zone was discovered in 1998 and consisted of high grade quartz float among talus, which graded up to 432 grams per tonne gold and 984 grams per tonne silver (Sable Resources website).
See Shasta for post 1996 work on the Shasta Chappelle (Baker) property.