French Peak silver-rich polymetallic occurrence, Fort Babine, Omineca Mining Division, British Columbia, Canadai

Regional Level Types
French Peak silver-rich polymetallic occurrence	Occurrence
Fort Babine	- not defined -
Omineca Mining Division	Mining Division
British Columbia	Province
Canada	Country

The French Peak occurrence is located north of the Suskwa River, about 11.5 kilometres west-northwest of Fort Babine on Babine Lake, and 51.5 kilometres east-northeast of Hazelton, British Columbia, in the Omineca Mining Division. Note that the Minfile co-ordinates are not correct; the ones given are based on Google Earth – the workings are clearly visible.
There is an extended description of the property on the British Columbia “Minfile” site, current to 2020, to which interested readers are referred. Relevant portions pertaining to geology are quoted below:
“Regionally, dacite, andesite and rhyolite subaerial to subaqueous tuffs and flows of the French Peak volcanics (Geological Survey of Canada Open File 2322), an informal subdivision of the Upper Cretaceous Kasalka Group have been subjected to complex block faulting and some low angle faulting. Recent government geological compilations indicate the deposit may be hosted in the Lower Cretaceous Rocky Ridge Formation (Skeena Group). [See the comment below.]
The French Peak occurrence area is predominantly underlain by bedded purple andesitic to dacitic lapilli, lithic and crystal tuffs. The southern portions of the property are underlain by andesite and rhyolite flows and tuffs, and rhyodacite. Generally, bedding strikes east-northeast with moderate (10-30 degree) northwest dips. The property covers an area of intersecting north-northwest and east-striking faults.
Mineralization consists of steep and low angle quartz-carbonate (siderite) veins and shear zones hosting tetrahedrite, argentiferous galena, chalcopyrite, sphalerite, and pyrite. The Ute vein system, containing coarse-grained galena and tetrahedrite, is located in shear zones in the bedded volcanic rocks. The main vein strikes east and dips steeply north to vertical. The vein system, apparently related to a major fault, has been exposed over a strike length of 457 metres and is of variable width. The system varies from a simple unmineralized break to broadly sheared areas, 1.5 to 4.5 metres wide, containing several veins and sulphide stringers with disseminated mineralization between them. Massive tetrahedrite, galena and chalcopyrite with disseminated pyrite was confirmed at depth along the vein structure which lies in a subaerial to subaqueous sequence of rhyolitic and andesitic flows and tuffs. Mineralized vein sections vary in width from less than 2 centimetres up to 1 metre. Rhyolitic rocks, in general, display considerable carbonate and sericite alteration and the matrix is highly clouded with hematitic(?) particles.
The Rio vein system, located 122 metres south of the Ute vein system, consists of massive, banded chalcopyrite, tetrahedrite and pyrite within a bedded rhyolite tuff unit. The vein system is essentially conformable with the tuff beds but appears to be controlled by bedding plane shearing. The vein strikes northeast and dips moderately northwest towards the Ute vein system.
The mineralized vein systems are surrounded by an alteration zone, from 1 to more than 30 metres in width, which consist of bleaching, manganese staining, silicification and clay alteration.
The Hematite zone, located 1100 metres southeast of the Rio and Ute vein systems, comprises a strong hematite-pyrite-clay altered zone containing several banded siderite-pyrite-quartz-chalcedony stringer veins within an andesitic tuff. Minor chalcopyrite-pyrite- tetrahedrite occurs. Drill core assayed 1.38 grams per tonne gold and 12.7 grams per tonne silver (Assessment Report 13834).”
Giles Peatfield comments:
This is an unusual deposit for the region. Of note is the fact that no igneous intrusive rocks have been identified in the immediate area. Intrusives a few kilometres to the west are mapped (Carter, 1981; Richards, 1990) as belonging to the Bulkley Intrusions, a widespread group of igneous bodies of Upper Cretaceous age. Richards reported a potassium-argon date on biotite, provided by N.C. Carter, of 71 Ma for the nearest intrusion to the French Peak deposit. Regarding the stratigraphic position of the deposit, contrary to the Minfile write-up given above, McIntyre (2001) preferred, based on fossil evidence, to place the deposit in the Middle Jurassic Saddle Hill Formation; further commenting that “The Saddle Hill Formation is the same age as host rocks for the Eskay Creek deposit and therefore, the French Peak area should be considered prospective for this type of deposit.” There are indeed some chemical and mineralogical similarities, but they are not marked, and Eskay Creek (Minfile No. 104B 008) is a very long way away. The main interest from a mineralogical point of view is the apparent compositions of various members of the tetrahedrite series found in the deposit – see a more detailed treatment of this in the mineral comments section below.
Official British Columbia records report that there has been a very small amount of production from the French Peak occurrence. Between 1964 and 1974, a total of 52 tonnes of hand-sorted material was shipped, although it is not clear where to. One would suspect the Cominco smelter at Trail, British Columbia, but this is not certain. The total returns quoted were: 12,488 troy ounces of silver; 4 troy ounces of gold; 8,940 kilograms of lead; 1,250 kilograms of copper; and 754 kilograms of zinc. There are currently no resource estimates available.
Giles Peatfield comments on the minerals reported:
This rather extensive list of minerals is compiled from a large number of reports. Many are field names, while others were identified by microscopy. In the latter case, this will be noted in the comments to follow. A few of the mineral identifications are tentative; again, this will be noted where appropriate.
Acanthite: Homenuke (1979), describing a polished section of material from the Ute Vein, noted that “. . . argentite [sic] was recognized in some of the galena . . . .” This is the only mention of the mineral in the references cited. Given the argentiferous nature of the galena from the deposit, it is not unreasonable to expect acanthite.
Amphibole group: Homenuke (1988), describing a specimen of “dacitic, welded lapilli tuff” reported “hornblende xtls”. There are no other mentions of the mineral in the references cited, but since most of the reporting concerned the metallic minerals this is not unreasonable.
Ankerite: Wells (2000), describing three thin sections cut from a mineralized specimen from the Rio Vein, reported that “The mineralogy in the three samples is quite similar with a bimodal gangue consisting of fine to medium grained mosaics of quartz and (ankeritic) carbonate.” This is the only mention of ankerite; all other reports refer to siderite (see comment below). Given that there are many references to manganese stains in the area, ankerite would be plausible.
Bornite: Wells (2000) observed “Rare fine bornite alteration of chalcopyrite . . . .”
Calcite: This was reported by Homenuke (1977, 1988).
Chalcopyrite: This is common and in places dominant – reported in essentially all the reports referenced.
Chlorite group: Homenuke (1977) reported “chloritic rock”; Homenuke (1979, 1989) simply reported “chlorite”, as did Wells (2000). Neither worker gave any more detailed information.
Epidote: Homenuke (1977, 1988) reported epidote in andesitic flow rocks.
Feldspar group: Homenuke (1979), describing rocks in the Rio Vein area, reported that “All sample rejects were stained for potassium. The only major potash feldspar bearing rock was in hole 18 where a crystal-lithic tuff was found to contain about 20% relict orthoclase or sanidine.” This is the only specific information regarding feldspars, although they must be common here.
Galena: This is a common constituent in the mineralized zones, in places reaching several percent levels. Close examination of available analytical data suggests that at least some galena here must be silver-bearing. Homenuke (1980), describing the deposit in general, noted that “The primary silver bearing mineral is tetrahedrite with secondary values in argentiferous galena.” See also note above for ancanthite and below for tetrahedrite group.
Hematite: Homenuke (1977) described a separate zone of mineralization which he called the “hematite zone”, and commented that “Further examination of rocks in the cat trenches showed the presence of chalcopyrite and tetrahedrite related to quartz-carbonate alteration in acid tuffs. The massive hematite appeared to be in conformable bands several inches thick.” He also noted that in one of the andesitic flow units, “Near the top of the unit the vesicles contain calcite, specularite and occasionally chalcopyrite.”
Kaolinite: Homenuke (1977, 1989) reported “kaolinization” in altered volcanic rocks, but gave no specific data.
Limonite: This has been reported in several reports. Wells (2000) listed it in a thin section description of altered volcanic rock.
Malachite: This has not been noted in most reports, but Homenuke (1988), describing specimens from his “Area 5”, mentioned a quartz-carbonate stringer zone with traces of tetrahedrite and malachite.
Marcasite: Homenuke (1979) identified marcasite in an argillaceous unit in the Rio Vein area, describing “. . . grains of iron sulfide which were definitely bedded as they followed slump structures and were quite rounded. Polished section study showed these sulfides to be accretionary marcasite, a normal occurrence [sic] in argillaceous sediments.”
Mica group: Most reports mention sericite as an alteration product. Homenuke and Seyward (1987) mentioned biolite [sic – presumably biotite] as a secondary mineral in altered tuff; Homenuke (1988) described biotite phenocrysts in an andesitic flow rock.
Owyheeite: Traces of this mineral were noted by Homenuke (1979) in polished section. His notes were “Euhedral pyrite in siderite, trace of owyheeite.” and “Pyrite in siderite with later owyheeite.”
Pyrite: This is common on the property; noted in several reports.
Pyroxene group: Homenuke (1977), describing chlorite in one of the andesite flow units, suggested that “The chlorite appears to be an alteration of augite.”
Quartz: This is common, especially in veins and alteration zones. Homenuke (1981) described “silicification”; Day (2000) reported “chalcedony”.
Rhodocrosite?: Homenuke (1977) wrote that in the deposits “Gangue minerals include quartz, siderite, pyrite, calcite and, probably rhodochrosite.” Several writers - see, e.g., Homenuke (1981, 1988); Homenuke and Seyward (1987); Day (2000); and Dufresne, et al. (2008) – have mentioned “manganese staining”, or “dendritic manganese”, but none have provided any more definitive detail. Manganese minerals would certainly seem to be indicated; detailed examination of the analytical reports in Dufresne et al. (2008) show a large number of sample intervals with elevated manganese contents, in some case up to several percent. These elevated values are often, although not always, from intervals with high base metal contents.
Siderite: This carbonate appears to be common in the deposit. It is mentioned in most of the reports studied.
Sphalerite: Essentially all the reports studied reported sphalerite. Homenuke (1981) recognized it in polished section. Analytical reports have values as high as several percent zinc, so the mineral is not unexpected.
Tetrahedrite series: This is the mineral assemblage of most interest in the deposit. Detailed compilation of analytical data from various reports has yielded an interesting pattern. First a caveat – the data are based on sampled intervals of drill core, not on individual mineral grain analyses. In many cases, although there are analytical data, there is no mention in the logs of tetrahedrite being noted – I have used only the intervals where the mineral was noted for this treatment; in all cases, the mineral was called “tetrahedrite” except for Wells (2000) who was careful to say “tetrahedrite-tennantite”. The analysis is based on the contents of As and Sb, reduced to molar values, to provide a molar As/Sb ratio. Of note is the fact that no other arsenic minerals have been reported here, and only traces of owyheeite (Ag3Pb10Sb11S28) with pyrite. A total of 15 separate analyses are represented in the study group. Of these, seven have molar As/Sb ratios between 0.20 and 0.48, suggesting tetrahedrite. The remaining eight samples have molar As/Sb ratios ranging from 1.88 to 23.86, suggesting tennantite.
In most cases, silver is strongly elevated in both the putative tetrahedrite and tennantite occurrences, but Homenuke (1988), describing specimens from his “Area 5”, noted that “A small outcrop with a braided stringer zone is present on the east side of a landslide. Considerable float from larger similar veins is present at the foot of the landslide. It is surprising that silver values are not higher in that some tetrahedrite blebs are up to 2 mm across. It may be that this tetrahedrite is low in silver compared to that in the Ute Vein System.” This is a problem, in that there are no laboratory reports included in Homenuke’s report. The silver values are quoted as being for the most part as less than 1.0 ppm Ag. This is puzzling, as the detailed analyses for silver derived from other reports on the property where tetrahedrite has been noted are generally several hundred parts per million (grams/tonne). Is it possible that the assays here were originally quoted in ounces per ton?
Tourmaline group: In describing alteration in the Ute and Rio vein systems, Homenuke (1977) wrote that “Similar features are associated with the Rio Vein System, with the additional appearance of tourmalinization related to the conformable mineralization.” He provided no specific information.
Further comment: One of the problems with this review has been that with few exceptions there has been a lack of specific analytical information regarding discrete mineral species. One has been forced in many cases to make judgements based on bulk analytical data or on nebulous descriptive writing. This would appear to be a situation with what might be a very interesting mineralogical story - perhaps a research project for a Master’s student?
Giles Peatfield comments on the rock types reported:
The French Peak deposit is contained in a volcanic and sedimentary sequence; the list of rocks given above has been derived from the various reports cited. Of interest is the apparent lack of intrusive igneous rocks.

Giles Peatfield
BASc. (Geological Engineering) University of British Columbia 1966.
PhD Queen's University at Kingston 1978.
Worked for Texas Gulf Sulphur / Texasgulf Inc. / Kidd Creek Mines - 1966 to 1985.
Vancouver based consultant 1982 to retirement in 2016

Other Databases

Link to British Columbia Minfile:	093M 015

Other Regions, Features and Areas containing this locality

References