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Bismuth Tellurides in British Columbia

Last Updated: 5th Aug 2019

By Richard Gunter

Bismuth Tellurides in British Columbia

Richard Gunter


Table of Contents:

Abstract:

Introduction

Geology and Mineral Genesis:

Bi-Te Mineralogy:

Localities in British Columbia:
White Elephant Deposit
Hedley Mining Area
Harrison Lake Area
Bear Lake Mine
Smithers-Terrace Area
Glacier Gulch
Vancouver Island
Merry Widow Mine
Mount Washington Mine
Texada Island
Southeastern British Columbia
CLY Prospect
Liddell Creek

Conclusions

References

Bismuth Tellurides in British Columbia

Abstract:

Bismuth tellurides are a suite of complex, layered, phases that occur in the lower temperature portions of quartz veins and massive sulphides that often have a significant enrichment in Au. The geology of the surrounding rock package has a relatively minor influence on the presence or absence of bismuth telluride minerals. The internal pH, fS and temperature of the veins are the primary indicators of the presence of bismuth tellurides, as opposed to other Bi and Te minerals.

In British Columbia several deposits contain various Te-Bi phases associated often with gold mineralization. The geology of the deposits in British Columbia range from: Au bearing quartz veins (White Elephant) and porphyry Au-Mo veins (Glacier Gulch) to Au skarns (Hedley). The deposits are not geographically or geologically defined and occur throughout the province in various ages of strata.

The mineralogy of the bismuth telluride phases is complex, even within one deposit. The published data on the Hedley gold skarns is the most complete in the province and illustrates the degree of overgrowth and intergrowth that these Bi-Te phases can incorporate within a single deposit. The other Bi-Te bearing deposits do not have as much published data so the identity of the Bi-Te phases is often extrapolated from a single analysis. These analyses can be suspect if they did not take into account the often intergrown nature of the Bi-Te phases.


Introduction:

“Bismuth tellurides are becoming common accessory minerals in a number of gold occurrences in this province” (Thompson, 1951)

Bismuth tellurides are a suite of metallic minerals that often accompany gold mineralization. They are layered compounds (Mineralatlas website: Tetradymite structure (2018)) with perfect cleavage, often mirror bright. The phases are often distinguished by their mode of stacking and are often impossible to distinguish macroscopically. In some of the literature (Scott, 1972) the author uses tarnish to distinguish phases. In one case the phases from the White Elephant Mine are differentiated with wehrlite (now pilsenite) tarnishing bronze and tetradymite tarnishing blue. Hedleyite often has a distinctly purple tarnish but it is not known if the other associated bismuth tellurides have a similar tarnish colour. Joseite and tetradymite often have a nondescript blue-grey tarnish. The perfect cleavage and embedded nature of most of the bismuth tellurides precludes using tarnish for most occurrences.

The common association of gold and bismuth tellurides means that the most occurrences of bismuth tellurides in British Columbia have been investigated for their gold content. This is common world-wide and has led to the recognition of bismuth tellurides in a significant number of localities, always in small amounts.

The classification of the bismuth tellurides has been attempted by a number of authors. Cook et al. (2007) and Cook et al. (2009) have the most recent classifications. Cook (2007) lists the various group members as: Bi-Te System, Tellurobismutite Isoseries, Tsumoite Isoseries and the Joseite Isoseries. Ciobanu (2009) concentrates on the chemistry of the Tetradymite Group (a subset of Cook’s Tellurobismutite Isoseries) and among the measured phases ha Of the 13 members of the Tetradymite Series (Cook, 2007) six are known to occur in British Columbia. These are: tellurobismuthite, tetradymite, hedleyite, pilsenite, joseite-A and joseite-B. Two type localities are in British Columbia; hedleyite at the Good Hope Mine, Hedley District and joseite-B at Glacier Gulch. Joseite A and B are not approved phases with the IMA but are used by Cook (2007) in his classification.

The original description of hedleyite (Warren and Peacock (1945) in Traill (1980) would not be considered valid in light of later classification in the bismuth tellurides. They discriminated the bismuth tellurides in their sample on the basis of SG and only used the highest SG flakes for the description of hedleyite.

Thompson (1949) lists the tellurium minerals found in Canada. The four chemical analyses Thompson provides for the White Elephant Mine tetradymite can be calculated to tetradymite-pilsenite percentages based on the sulphur volumes. They are one analysis at 100% tetradymite-0% pilsenite; two analyses at 94% T - 6% P and one analysis at 80% T- 20% P. It is not known if these are oriented intergrowths but it is possible. The Thompson article intimated that the samples are the foliated massive tetradymite phase and not the bronzy tarnishing, slightly harder and less malleable pilsenite.

Modern (post 1960) analyses of the non-Headley Mines bismuth tellurides are lacking. The British Columbia government mine database (Minfile) has data on all of the localities. The data is a compilation and thus not intensive for mineralogy. The presence of bismuth tellurides are generally noted by their physical properties but their mineral species is often not quantified; only their presence.


Geology and Mineral Genesis:

In British Columbia the presence of bismuth tellurides in gold is fairly widespread with a range of phases in different localities. In most cases the geology of the bismuth telluride deposits are skarns or polymetallic deposits but some are simple quartz veins with minor Fe sulphides. The areas carrying bismuth tellurides in quartz veins tend to be those where Tertiary plutons invade Paleozoic siliceous and calcareous metasediments and form hornfels/skarns.

Often large areas associated with major regional fault structures will have suites of quartz veins with gold and bismuth tellurides. An example of such an area is the Harrison Lake Fault in southwestern British Columbia. The fault traverses complex geology in the northern Cascade Range and has Bi-Te mineralization associated with gold on both sides of the border. Other Bi-Te deposits in British Columbia are also associated with deep-seated regional fault systems. Orogenic gold deposits which contain the Bi-Te phases have been determined to originate by tapping fluids released from subduction zones and thus are directly related to these major faults (Groves et al. (2019)).

Other areas of bismuth telluride-gold deposits such as north-east Russia commonly occur at shallow depths with their deeper seated counterparts having different mineralogy (Viketeva et al., 2018). The higher level sub-volcanic telluride-gold deposits are rare in British Columbia. More common occurrences are zoned low to high temperature skarn-dominant districts described in the Bridge River area for example (Moore, Hart and Marsh (2009)). The very shallow-depth exposures of mineral deposits exist in British Columbia, especially in the Stewart are of the north-eastern part of the province.

It appears as if the metamorphic grade of the enclosing sediments has an influence on the presence or absence of bismuth tellurides. Very low-temperature deposits, such as those in the Cobalt, Ontario district, have abundant native bismuth but no bismuth tellurides. Epithermal gold deposits such as the Lone Pine deposit in New Mexico has abundant native tellurium but no bismuth tellurides. High temperature deposits, unless they have a mid-temperature sulphide melt component, will not have bismuth tellurides. In most of these the bismuth and tellurium is tied up in sulphosalt inclusions within galena.

There are many areas where the geology of the surrounding rocks should be suitable for the presence of bismuth tellurides but detailed exploration has not taken place and data is lacking. The presence of bismuth tellurides without significant gold mineralization can occur. The White Elephant deposit has abundant bismuth tellurides but was not successful as a gold mine. Other areas such as the Bridge River District have gold and antimony/bismuth minerals in separate deposits. The quartz veining that produces most of the bismuth telluride samples is characteristic of the gold deposits in British Columbia and the disseminations of bismuth tellurides as inclusions within sulphide, such as Bi-Te bearing galena that occurs in European deposits, are rare in British Columbia.

Overpressure zones within the mountain building terrains of the western Canadian cordillera are the primary focus of the medium-grade and epithermal Au-Ag deposits (Dube and Gosselin (2007)). These structures never have enough volume or grade to qualify as base-metal deposits, though they often contain significant Pb-Zn mineralization. The overpressure zones produce abundant quartz-carbonate-adularia veining, often in stockwork, and these structures contain the Ag-Au deposits. Bismuth, tellurium, arsenic and often tungsten are minor phases within the Au-Ag deposit structures and are often present as minor minerals and as tracer elements in geochemical investigations of this deposit type. The geology of each of the bismuth telluride localities will be different in detail so there is no consistent geological setting that will correlate with the species of bismuth telluride. It appears as if in-deposit conditions are similar enough for each locality that there is no zonation of bismuth telluride species, regardless of the immediate host rock lithology.

There are many references to bismuth tellurides in the literature that do not have detailed mineralogical data and so are assigned a name based on inadequate evidence. The Bi-Te deposits that have been mineralogically investigated often have two or more Bi-Te phases as intergrowths so only detailed mineralogy can identify the Bi-Te phases in an individual deposit. The Bi-Te intergrowths are non-reactive and only a few localities have distinct, mono-minerallic, bismuth telluride aggregates.

Bismuth tellurides are always a late-stage addition to the quartz vein assemblage and seldom occur in the host rock. In skarn assemblages such as the Nickle Plate Mine at Hedley the bismuth tellurides occur within calcite-filled pores of the calc-silicate skarn. The bismuth telluride aggregates are normally platy in outline so do not represent a quenched melt, which would produce sub-spherical aggregates or veinlets along the quartz grain boundaries

The melting points of pure bismuth telluride minerals are moderate: tellurobismuthite melts at 585oC and tsumoite melts at 540oC. Initial melting of the bismuth telluride rich deposits begins at < 350oC @ 1 bar (Tomkins et al. (2006)). Many studies have been completed on the melting of base-metal sulphides and Pb-As sulphosalts, mostly in reference to melting within massive sulphide deposits and not quartz-dominant deposits. There has not been much study of the possibility of melt veinlets in meta-sedimentary/metavolcanic rocks containing bismuth tellurides.

An example of a sulphosalt mixture produced by sulphide melting was exposed in the Lower East Stope of the Chisel Mine in 1985. A fold nose containing very coarse grained sphalerite occurred adjacent to a more brittle layer of massive, coarse grained pyrite. A 1 meter thick layer between the sphalerite and the pyrite had an aggregate of medium to coarse grained galena-boulangerite-meneghinite-argentian tennantite (Gagne et al. (2007)).

Polished section and microprobe investigations in the Lalor Mine (Duff (2016)), which is adjacent to the Chisel Mine and thus has the same regional P/T conditions, gives more details of slightly different sulphosalt chemistry. Duff does not mention sulphosalt melting as a source for the Ag-Au-rich sulphosalt aggregates but many of the textures illustrated in polished sections from the Lalor Mine are identical to those in Gagne (2007). The tellurides at the Lalor Mine are Au-Ag tellurides with little bismuth in any of the phases analyzed. Bismuth telluride melt veinlets have been noted in the South Range deposits of the Sudbury Basin; they are noted as a collector of PGE minerals in low-sulphide deposits.

The evaluation of gold deposits worldwide has led to many studies of the bismuth tellurides and their contributions to the concentrations of gold and platinum group elements. A recent grouping of gold deposits characterized by reducing conditions and the presence of pyrrhotite (indicating low fS2) has proven to contain the bulk of the bismuth telluride mineralization. This type of gold deposit is noted as occurring widely in southern British Columbia. A publication on skarns in British Columbia (Ray 2013) allows for the differentiation between Bi-Te bearing pyroxene-pyrrhotite Au skarns and non-Bi-Te bearing garnet-pyrite Au skarns.

Low fS2, as noted by the presence of pyrrhotite, has been noted with the bismuth tellurides in a number of British Columbia gold occurrences. Many deposits, such as the pyrrhotite-lollingite-bearing Hedley District mines, are notably low in total sulphur. The low sulphur-high Te and Se appear to be connected to the relatively low temperature of formation of the deposits. Even massive sulphide deposits containing Se such as the Bornite Zone in the Kidd Creek Mine, Ontario has been determined to be the lowest temperature portion of the deposit; with separate Se minerals associated with lowest temperature quartz veins. The Bornite Zone does not contain pyrrhotite as the Total Iron content is very low. The U-Se deposits in Saskatchewan and elsewhere are also having demonstrable low sulphur and have a similar large number of phases in the suite of Se containing metallic minerals.

Recent work on vapour phase transportation indicates that under certain conditions tetradymite can be part of the late-stage gold paragenesis of a subvolcanic enargite-pyrite deposit, such as at the El Indio, Chile volcanogenic Cu-Au deposit (Henley et al. 2012). They found that the early pyrite-enargite phases were transported by vapour and it was only after a pressure decline, below the threshold for liquid water, that the phases in the gold paragenesis (including bismuth tellurides) could be deposited. There are few of these high-level subvolcanic deposits in British Columbia that have been discovered by data that is coming from the Stewart area of northwestern British Columbia suggests that such deposits exist but have not been fully characterized.

The presence of low-temperature phases within a gold paragenesis is a normal part of low-sulphidation suite. Not all of the late phases are bismuth-bearing. Native Tellurium is not uncommon in some gold deposits, such as the Emperor Mine, Fiji, and a suite of antimony phases is probably more common than the bismuth suite. The Neue Hoffnung Gottes Mine, in Braunsdorf, Saxony, for example has a late-hydrothermal suite of stibnite-bertherite-kermesite in quartz veins overlying the Ag-Au-Cu-Pb-Zn polymetallic paragenesis. The bismuth telluride mineral suite is a specific sub-set of these late-stage, lower temperature, mineral phases.

Large-scale investigations of gold-telluride deposits (2003-2008), mainly in Europe and Asia have been summarized by Cook et al. (2009). The results of the investigations illustrate the complex interplay of redox conditions (pyrrhotite-magnetite (reducing) verses pyrite-hematite (oxidizing)) and temperature as controls on different Bi-Te assemblages (mostly stable with native bismuth) and their differentiation from the associated Au-Te paragenesis. The presence or absence of Bi-Te phases is therefore not governed by the bulk chemistry of the deposits, as Bi and Te mineral parageneses exist without the presence of Bi-Te phases.

The parageneses of the late-stage, metamorphic gold-quartz veins is often different from the above mentioned epithermal deposits. In these deposits the gold and tellurides, including Bi-Te phases, is remobilized by metamorphic processes from the surrounding meta-sedimentary and metavolcanic rocks. The segregation of gold is not always confined to the quartz-bearing veins; however the Bi and Te bearing phases normally are confined to the quartz veins. This may be due to lower melting temperatures of the tellurides and their greater mobility under metamorphic conditions.

Bi-Te Mineralogy:

Bi-Te minerals are some of the most complex mineral structures so far described. They are layered structures with variable thicknesses of Bi and Te +/- S layers that make up the variable proportions of Bi and Te in their formula.

There have been several attempts at classification, mentioned in the Introduction. Cook et al. (2009) says: Our compilation of ~900 published results of analyses for minerals of the tetradymite series (tellurobismuthite, tetradymite, guanajuatite, paraguanajuatite, kawazulite, skippenite, tsumoite, hedleyite, pilsenite, laitakarite, ikunolite, joséite-A, joséite-B) allows compositional fields among naturally occurring Bi–Te–Se–S compounds to be established. New compositional data for ingodite, laitakarite, pilsenite, kawazulite and tellurobismuthite extend previously known compositional limits. Recognized minerals can, for the most part, be satisfactorily and conveniently classified according to the ratio Bi(+ Pb)/(Te + Se + S), into the subsystems (isoseries) Bi2Te3–Bi2Se3–Bi2S3, Bi4Te3–Bi4Se3–Bi4S3 and BiTe–BiSe–BiS. Most minerals show limited compositional variation, but this is generally more extensive in the Se-bearing phases (e.g., laitakarite) and in certain members of the system Bi–Te, such as hedleyite and tsumoite. Substitution of minor Pb for Bi is widespread throughout the group, especially in the Bi4Te3–Bi4Se3–Bi4S3 subgroup.


Several possible additional minerals or compositional variants of existing minerals would appear to exist in nature, including Bi4Te2Se, Bi4Te(Se,S)2, Bi3Te2Se and Bi3(Te,S,Se)4. Within the above groups, Bi(+ Pb)/(Te + Se + S) stoichiometry is remarkably constant, in accordance with known and derived structures in which all phases (except those in which Pb is essential) can be envisaged in terms of various combinations of nonvalent five-atom Bi2X3 and two-atom Bi2 layers. Deviation from Bi(+ Pb)/(Te + Se + S) stoichiometry within the isoseries may be linked to stacking disorder. Noting the appearance of many other phases and stoichiometries in experimental work in the system Bi–Te–Se–S and its subsystems, as well as the homologous character of this series, we predict that a significant number of additional mineral phases exist in nature and will be discovered in the future. Many of these, however, cannot be identified by chemical microanalysis alone. They give compositional ranges of the various mineral phases, such as hedleyite, pilsenite etc., but not localities.

Cook et al. (2009) says: Mixed-layer compounds from the tetradymite group, in the range Bi2Te3-Bi8Te3, were studied by HRTEM. The formula S′(Bi2kX3)·L′[Bi2(k+1)X3] (X = chalcogen; S′, L′ = number of short and long modules, respectively) was introduced as a working model. Diffraction patterns show that all phases are N-fold (N = layers in the stacking sequence) superstructures of a rhombohedral subcell with c/3 = d1 ~ 0.2 nm. The patterns, with two brightest reflections about the middle of d1*, are described by monotonic decrease of two modulations with increase in Bi: (1) q = γcsub* (q ~ homoatomic interval; γ = 1.8–1.64 for analytical range; csub ~ 3d1), based on displacive modulation between chalcogen and Bi atoms; and (2) qF = γFcsub*; qF = (i/N)d1* = idN*, i = S′ + L′, relating changes in module size and number to displacements in a basic substructure.

The qF model, besides underpinning the stacking sequences, was adapted to incorporate the homology for S′, L′ modules related by k. The displacements are quantifiable by fractional shifts between reflections in the derived and basic structures. The condition for “the brightest two reflections about the middle of d1* to be separated by idN*” is fulfilled only if the shift at this position is minimal (equal to 1/Nb; Nb = layers in the basic structure). This model and accompanying program compiled to find suitable Nb and simulate intensity pattern(s) can be used to (1) constrain stacking sequences estimated from observation; (2) predict polysomes as larger building blocks; and (3) discriminate single-phases from random polysomes. The formula nBi2·mBi2X3 describing the configuration for Bi2kX3 modules by n/m = k – 1 is proven by lattice fringes, but is not underpinned by qF and does not constrain assumed homology. This study included HRTEM studies on a sample of hedleyite from the Good Hope mine, Hedley, British Columbia.

The HRTEM study illustrates the complexity of bismuth telluride mineralogy at Hedley. Intergrowths and overgrowths of one bismuth telluride phase by another, detectable only by sophisticated machines, are common here. This makes older bismuth telluride analyses from the Hedley deposits questionable as the homogeneity of the samples is often suspect. The layered nature of the bismuth tellurides leads to stacking defects parallel to {0001} that result in different Bi/Te ratios within individual crystal grains.

There are currently 13 recognized members of the Tetradymite Group with: hedleyite, joseite A and B, pilsenite, tellurobismuthinite and tetradymite recognized as occurring in British Columbia. In several cases in British Columbia, such as: the Nickel Plate Mine, the Glacier Gulch locality and the White Elephant Mine, at least two, and sometimes three, Bi-Te phases occur in apparent equlibrium in one deposit. Kitakaze (2017) in his synthesis of the BiTe-BiS pseudobinary system indicates that multiple Bi-Te phases are present at 390oC. He has pilsenite (called wehrlite)+tetradymite+joseite-B in equilibrium in his diagram. In several other portions of the diagram two Bi-Te phases are present.

The sharp delineation of mineral phases and presence of more than one Bi-Te phase in many deposits illustrates that only short-range equilibrium is prevalent. This may be caused by local Eh/pH conditions affecting the growth stacking. As Bi-Te phases are almost always late,-or latest, in the paragenetic sequence within the veins they are formed at lower temperature than most of the sulphides/sulpharsenides and occur intergrown with Native Gold.

The Bi-Te phases most often occur a 2 mm or smaller metallic, platy crystals encased in quartz. In many cases the bismuth tellurides occur in veins with relatively few other sulphides so they do not occur as inclusions within galena or chalcopyrite. In the Hedley skarn district, in the French Mine for example, hedleyite and lollingite occur as crystals within pore spaces of the grossular-diopside skarn as separate grains that are not intergrown. The Tetradymite Group phases can be easily identified in hand samples by their prefect basal cleavage and low hardness (All of the phases have hardness between 1 ½ and 2 (Mindat.org locality pages, 2018)). Prior to the advent of microprobe analyses the distinction of the various phases of bismuth tellurides was difficult as they are all identical in polished sections.

There has been considerable discussion in the earlier (pre-1970) literature on the use of tarnish on un-cleaved grains to determine the different members of the Tetradymite Group. Early descriptions such as Thompson (1949) used it to distinguish some of the bismuth tellurides. Scott (1971) says the Glacier Gulch joseite is dull grey-black with iridescent overtones and the White Elephant pilsenite tarnishes bronze while the co-existing tetradymite tarnishes blue. Tarnish may be useful locally as at the White Elephant deposit to discriminate between co-existing Bi-Te phases that are indistinguishable on a fresh surface but there are too many factors to make it applicable on a larger scale.

The platy crystals of bismuth tellurides can look very much like coarse-grained euhedral crystals of molybdenite. Both molybdenite and the bismuth tellurides have perfect basal cleavage. The bismuth tellurides on average are slightly harder than molybdenite (H 2-2.5) and the cleavage planes are straight and mirror like while the molybdenite cleavage (H 1-1.5) planes are often distorted and wavy. In most cases the bismuth telluride minerals and molybdenite do not occur in the same deposits so both phases do not occur together. Platy metallic crystals with prefect basal cleavage from an unknown deposit must be analyzed by XRD in order to distinguish the phase present.

No one since Thompson (1945) has attempted to catalogue all of the Canadian telluride occurrences. Traill (1980) catalogues all Canadian minerals by species but his mineral descriptions are not complete and he often copies old analytical data. There is not a more modern compilation of chemical or mineralogical data for the bismuth tellurides from Canada. This is unfortunate as there have been many advances in the classification of bismuth tellurides and the chemical data provided needs additional measurements to be useful for modern classification.

Most existing chemical data will have been done using wet chemistry on bulk crystal samples so the in-crystal variations in chemistry will not have been detected. This leads to the current state of chemical analytical results which are not stoichiometric and possibly represent two or possibly three intergrown stiochiometric phases. There has only been modern analysis completed on hedleyite from the Good Hope Mine to illustrate the potential intergrown nature of the bismuth tellurides. Thus all identifications of individual species from the other localities may represent some degree of intergrowth with other minor Bi-Te phases.



Localities in British Columbia:

Bismuth telluride localities in British Columbia have been noted in conjunction with ore mineralogy in a number of publications. In a series of articles in the American Mineralogist from 1950 to 1954 Thompson listed ore minerals in Western Canada and included a number of bismuth tellurides. In 1950 he listed Wehrlite from the Ajax Claim; in 1951 he listed hedleyite and joseite from the French (Oregon) Mine, Hedley District and tellurobismuth from the Fil-Mil Claim, Vancouver Island; in 1953 he listed tellurobismuth from the Lucky Jim Mine, Quadra Island, tetradymite from the Katanga Group, Pitt Lake and wehrlite from Jones Creek, 12 miles west of Hope; in 1954 he listed rickardite, empressite and native tellurium from the Grotto Group, Hardscrabble Creek in the Skeena area. In addition to tellurium and the bismuth tellurides he listed a number of other rare ore minerals. These localities listed in the American Mineralogist have few other citations in the literature and are not of collector quality for bismuth tellurides.

Some localities for British Columbia bismuth tellurides are mentioned in Traill (1980) but the data is generally only as a copy of what Thompson has noted. The Geological Survey of Canada Series on Regional Mineralogy has a paper on mineral collecting in British Columbia (Leaming, 1973). It is a brief review of British Columbia mineralogy and has only the Hedley District and the White Elephant deposit listed under collector-quality bismuth tellurides.

More recent investigations of British Columbia bismuth tellurides (Cathro and Lefebure, 1999) concentrate mainly on geochemical Bi and Te data rather than the mineralogy of the bismuth telluride phases. Bismuth and tellurium are considered pathfinder elements for orogenic gold deposits so less attention is paid to the mineralogy of the phases than their geochemical abundance. The lack of detailed mineralogical data in these reports makes identification of the bismuth telluride phases impossible.

With the rise in the price of gold almost all formerly producing gold deposits in British Columbia are being evaluated for additional or enhanced reserves. This exploration gives more publically available data and the rigor of the NI 43-101 reports requires the gathering of mineralogical and chemical data to provide backup for reserve calculations.


White Elephant Deposit:

The White Elephant Deposit is one of the bismuth telluride deposits mentioned by Scott (1971). It is an abandoned small-scale gold mine with quartz and pyrrhotite in the dumps (okanaganlakebc website 2007). British Columbia Minfile (2018) says: The White Elephant showing is located 25 kilometres west- southwest of Vernon, north of Shorts Creek.

In this area, Middle Jurassic granitic rocks of the informally named Terrace Creek batholith intrude Devonian to Triassic sedimentary and volcanic rocks of the Harper Ranch Group. Eocene Penticton Group volcanic and sedimentary rocks cover the older units.

A quartz vein or lens in granodiorite hosts gold, silver, tungsten, bismuth and tellurium. The highly fractured and faulted quartz vein strikes northeast and dips 60 degrees northwest. The vein, greater than 10 metres thick, is traceable on surface for at least 30 metres. A pod of massive pyrrhotite, up to 4 metres thick, occurs at the footwall contact, although the best gold values occur in lenses and stringers some distance from the vein wall. Pyrrhotite, pyrite, chalcopyrite and tetradymite (gold-bearing bismuth telluride) occur as lens-like bodies with the vein. Stringers and segregations of bismuth telluride, free gold and scheelite are also reported. Ore-shoots are up to 7.5 metres thick and 15 metres long. Underground workings include a 91-metre inclined shaft with four levels of development to a depth of 60 metres.

In 1921, a 2-metre shaft had been completed and in 1922 about 264 tonnes of mineralized rock were shipped producing 5,257 grams of silver and 13,468 grams of gold. In 1924, Okanagan Premier Mines Ltd. extended the shaft to 30 metres and drove a 60-metre crosscut. In 1928, Pre-Cambrian Mines Ltd. continued underground exploration and in 1929, mining from the pyrrhotite lens produced 27 tonnes of pyrrhotite concentrate, containing low gold values. Production from the quartz vein during the period 1933-35, totalled 4882 tonnes and produced 4,292 grams of silver and 49,702 grams of gold.

Thompson (Am. Min 1949) says: In British Columbia, at the White Elephant Claim, Okanagan Lake, Vernon Mining Division, in several specimens of white quartz containing a soft massive mineral with a bronzy tarnish (wehrlite) and a soft platy mineral (tetradymite);

Traill (1980) mentions wehrlite from here but does not provide analyses. He mentions tetradymite from here as well, associated with wehrlite, and gives three analyses: (1) by Forward, Bi 59.10, S 4.85, Te 35.90, t o t a l 99.85; (2) by Williams, Bi 60.72, 60.88, S 4.29, 4.29, Te 34.71, 34.47, t o t a l s 99.72, 99.64; (3) by Williams, tetradymite with minor wehrlite, Bi 61.05, S 3.65, Te 35.10, total 99.80 (H.V. Warren, 1946: Univ. Toronto Stud., Geol. Ser., 50 p. 77). He also indicates that the wehrlite is bronze tarnished and the tetradymite is blue tarnished and massive.


What remains of the White Elephant shaft in 2007 can be seen on the website from www.okanaganlakebc.ca website. It is an uncovered shaft with no infrastructure remaining.

According to Scott (1971) the major bismuth tellurides were wehrlite (now pilsenite) and tetradymite. He says that the good samples such as

Image 1

Pilsenite Crystals in Quartz, White Elephant Mine were found during early mining and are not present on the dumps. This sample has the bronzy tarnish that is characteristic of pilsenite from here.

The White Elephant deposit is an example of a simple quartz vein system that has marginal amounts of gold and a significant volume of two co-existing bismuth telluride phases. There is not enough data to indicate if the pilsenite-tetradymite phases were zoned within the ore body but they appear to be crystallized as separate grains and not intergrown. The separate grains are often isolated and roughly euhedral.

Samples of the White Elephant Mine pilsenite-tetradymite from the literature are: Minerals Unlimited website, April 26, 2005 says: PILSENITE – Canada: WEHRLITE. Metallic grains. lean, in quartz. Bart Cannon in his Spring 2005 list indicated that Tellurobismuthite (Bi2Te2Te) occurs at the White Elephant Mine, Ollala, British Columbia. New Dana says the telluride mineral from White Elephant Mine is only tetradymite, without mentioning the presence of the second phase. Traill has “foliated tetradymite occurs intimately associated with wehrlite in a quartz body, with pyrrhotite, chalcopyrite and free gold, 15 miles southwest of Vernon at the White Elephant Mine”

The Rare Minerals portion of Dakota Matrix, January 16, 2009, has a sample of a single crystal of the platy telluride, with a tarnished surface, in a gelatine capsule. It has a note: Pilsenite var. Wehrlite #19459 White Elephant Mine, Vernon, British Columbia, Canada: Ex. S.G. Baker Collection: Elements: Bi Te: Metallic plate of Pilsenite var. Wehrlite in capsule. Overall 6 x 3mm. $50.00. . The pilsenite sample here has the same tarnish as both of the Dakota Matrix samples. A matrix sample, with the location card designation of Okonogan Lake, is for sale in the Wienrich auction July 22, 2009. The note says: Massive metallic "wehrlite" is rich throughout this 4.1 x 3.1 x 2.3 cm matrix with minor tetradymite. It has an identical tarnish and separate pseudohexagonal platy crystals as this sample with a minor massive phase. This data appears to be in line with the Thompson results.

Scott (1971) mentions the White Elephant and says that modern mineral finds are 2 to 3 mm in size but larger crystals and fist-sized masses were found during the original mining. He has determined that both wehrlite (pilsenite) and tetradymite occur here. Pilsenite tarnished bronze and tetradymite tarnishes blue.

There appears to be no published chemical analyses for wehrlite (pilsenite) from the White Elephant Mine so the current designation of pilsenite is derived from the former designation of wehrlite rather than from published chemical data.


Hedley Mining Area:

The Hedley Mining Area is in southern British Columbia, east of the Cascade Mountains and just north of the Canada/U.S. border. It contains several mines within a large, world-class, gold skarn deposit. The various mines have slightly different silicate mineralogy, mainly varying garnet/pyroxene ratios, but the bismuth tellurides are homogeneous system wide. The Nickel Plate Mine was an open pit with the other deposits mined underground.

Thompson (1949) says (under Hedleyite): This species (Hedleyite) was described by Warren & Peacock (1945) from the Good Hope mineral claim, Hedley, British Columbia. Hedleyite occurs as thick plates often intercalated with joseite B, native bismuth, and gold, and associated with arsenopyrite, molybdenite, and pyrrhotite, in quartz and skarn.

Thompson (1949) also says (under Joseite): In Canada the occurrence of joseite B has been confirmed in British Columbia at Glacier Gulch, Hudson Bay Mountain, near Smithers, where it is associated with bismuth and joseite A; and at the Good Hope mineral claim, near Hedley, Osoyoos Mining Division, where it occurs as coarse plates often intergrown with native bismuth and associated with hedleyite, pyrrhotite, arsenopyrite, molybdenite, and gold, in quartz and skarn.

Thompson (1951) has a note on the hedleyite and joseite from the French (Oregon) Mine, Hedley District. He says the bismuth tellurides occur with native bismuth, molybdenite and gold.

Scott (1971) does not mention the Hedley area mines in his article on sulphosalts. He misses several of the better British Columbia sulphosalt localities including Cawston (acanthite-native silver) and Cariboo Gold Quartz Mine (cosalite and galenobismutite).

The Hedley District is one of the most complex Bi-Te skarns and a primary example of a gold skarn. The geology and some of the mineralogy is mentioned in the Mindat article on Tungsten Skarns in British Columbia.

The Hedley area Au-Bi-Te skarns have been described in detail in several publications on the skarn mineralization and on the mineralogy of the bismuth tellurides. The hedleyite mineralization is complex in detail and often occurs in multi-phase grains that require chemical and mineralogical testing to sort them out. The Hedley District contains several mines. Oregon (French) Mine; a gold-bearing skarn deposit on a mountaintop 2 kms east of Hedley, north Highway 3 in southwest B.C. and the Nickel Plate Mine, directly above the town of Hedley are the major mines recorded in the literature. They are both part of one skarn-producing system.

A good example of the Hedleyite/Joseite-bearing skarn is

Image 2 Hedleyite in Skarn, Oregon Mine

It is described as 5 cm x 4 cm mass of medium to fine grained grey-green garnet skarn with elongate, disseminated 1 cm grains of Arsenopyrite, Loellingite, Gersdorffite and bronzy Pyrrhotite. There are several partially exposed 2 mm cubes of Cobaltite. Tarnished grains of Hedleyite and the untarnished brilliant Joseite-B are associated with the Arsenopyrite-Gersdorffite grains according to the B.C. Minfile database. The telluride grains are small and few compared to the other Hedley samples. Thompson (1949) in his survey of Canadian telluride occurrences says Joseite tarnishes lead grey and Hedleyite tarnishes iron black. The RRUFF Hedleyite sample has iron black tarnish on a darker reflective body. It has been identified by single crystals XRD, but has no chemistry. The 2009 Am Min article illustrates these as an intergrowth of Hedleyite and Joseite-B and says Hedleyite is the more common mineral. The skarn has small Calcite filled pockets with micro telluride and gold crystals lining them that can be observed once the Calcite is removed.

Some of the Joseite-B grains have triangular faces, in keeping with their hexagonal crystal structure. There are small areas of red, metallic massive Pyrargyrite on the shear faces of the sample. It seems odd to have Pyrargyrite when all of the other phases are arsenic rich but that is the species given in Minfile. There are areas of < 1mm euhedral dark to medium brown Grossular-Andradite garnet in the greener portions of the skarn. The iron content of the skarn decreases with distance toward the center of the skarn so this is a proximal skarn sample.

Dave Joyce in a recent website says that Joseite-B and Hedleyite both occur at the Good Hope Mine at Hedley and they had to microprobe the samples in order to determine which species was present. His photos seem to illustrate a clear distinction between the tarnished Hedleyite and the untarnished Joseite-B grains. If the Thompson data is applicable to the weathered samples then the alteration should tell the telluride minerals apart.

British Columbia’s Minfile has an entry on the Nickel Plate Mine which contains: Grain boundary relationships suggest the following three stages of sulphide deposition: (1) pyrite; (2) arsenopyrite and gersdorffite; and (3) pyrrhotite, chalcopyrite and sphalerite. Gold mineralization is related to the latter two stages, and minor amounts of magnetite are associated with the first and last sulphide phases. Pyrrhotite and arsenopyrite are the most common sulphides. Present in lesser amounts, but locally dominant, are pyrite, chalcopyrite, and cadmium-rich sphalerite with minor amounts of magnetite and cobalt minerals. Trace minerals include galena, native bismuth, gold, electrum, tetrahedrite, native copper, gersdorffite, marcasite, molybdenite, titanite, bismuth tellurides (hedleyite, tetradymite), cobaltite, erythrite, pyrargyrite and breithauptite. Trace amounts of maldonite have recently been identified. The native gold, with hedleyite, occurs as minute blebs, generally less than 25 microns in size, within and adjacent to grains of arsenopyrite and gersdorffite.

Several rare-mineral websites carry samples of Hedleyite. A photo on one is almost identical to this sample and says the sample contains yellow tarnished flakes of Hedleyite and bright flakes of Joseite with quartz and amphibole. Excalibur Minerals has a sample of Hedleyite from a skarn prospect pit of the Good Hope Group, 6 kms SE of Hedley B.C. The sample contains flattened silvery metallic masses scattered in greenish skarn matrix with minor Bi and other minerals. (The Good Hope Group has coarse Hedenbergite pyroxene so the sample is from the Nickel Plate Mine.). The 1996 Geology of Canadian Mineral Deposit Types says that the deposit is layers of garnet and pyroxene-rich skarns mineralized with: Gold together with arsenopyrite, pyrrhotite and pyrite together with anomalous Bi-Te-Co is concentrated in the latest stage, a retrograde quartz-calcite-epidote-sulphide assemblage deposited near the skarn-marble boundary. The article says there is no significant Cu in these skarns but Mindat.org has Chalcopyrite at Nickel Plate. A cross-section of the Nickel Plate deposit illustrates the garnet:pyroxene ratio and the Au>3 g/t + Bi, Te, As, Fe limit (probably the grade cut-off) with a cross section of the open pit. A map of the immediate mine area shows the open pits in relation to the intrusions and the Hedley Formation limestones. This is probably the lower grade skarn units as it lacks the coarse-grained Quartz lenticles.

The original description of Hedleyite (Warren and Peacock; 1945) says: Hedleyite is associated with native bismuth, joseite, pyrrhotite, arsenopyrite, calcite, and gold. Bismuth is conspicuous in some samples but joseite cannot be distinguished from hedleyite by inspection. Pyrrhotite and arsenopyrite in small amounts occur in the skarn near the quartz veins. Calcite is sporadically scattered through the veins and stringers. Visible gold occurs close to the bismuth minerals, sometimes as films in the foliated tellurides. The ore minerals are notably poor in sulphur and thus it is evident that the mineralizing solution was deficient in sulphur. The presence of occasional quartz crystals projecting into cavities in the gangue indicate that the temperature of mineralization was low to moderate. There was no indication of secondary minerals in the article but the samples were sent from the mine manager and was not collected by the author.

David Joyce has a photograph of Cobaltite from the neighboring French Mine that is identical to the crystals on this sample. He has a suite of samples from the Nickel Plate Mine containing coarse Gold, Hedleyite and Joseite in Quartz. His microprobe study has ascertained which tellurides were which in his particular samples. He does not say whether the results of his study are applicable to the Nickel Plate tellurides as a whole.

The main occurrence of hedleyite in the district is in the quartz veins with minor sulphides. An example from the Nickel Plate Mine is

Image 3 Hedleyite plates in Quartz.

It is described as 3 cm x 4 cm masses of Quartz with 1 cm altering Arsenopyrite or Lollingite with tabular Hedleyite crystals, one group free growing in a vug and another, to 1 cm, embedded in the Quartz, other primary phases including purple black, sectile, octahedral crystals that may be Maldonite and veinlets of unidentified green secondary minerals. The 1 mm purple tarnishing Hedleyite grains and a suite of platy metallic crystals that is distinctly less tarnished, possibly Joseite-B, occurs at the edge of the Arsenopyrite/Lollingite masses, next to the Quartz. There are several edges of platy Hedleyite crystals to 1 cm in one of the Quartz cavities. The distinct parting on the arsenide mass indicates that this may be Lollingite. Pinkish tarnish on some of the 0.5 cm equant crystals indicate that there may be Native Bismuth on the sample embedded in Quartz.

These samples have undescribed secondary minerals on the surface. They may be Tellurates as there is little sulphur in this system. An example is:

Image 4 Nickel Plate Mine Secondary Minerals.

It is described as 3 cm x 4 cm mass of quartz, purple tarnishing Hedleyite and very bright yellow Gold. This sample also has green secondary minerals on the surface. It is possible most of the “Arsenopyrite” identified on the sample may be Hedleyite and some of the yellow phase, directly associated with Hedleyite, may be Gold while the remainder is Chalcopyrite. This sample is very different in appearance from sample (a). The purple tarnished phase is crinkled and not fractured as is the Arsenopyrite. Neither the purple phase nor the yellow phase directly associated with it have sharp edges, all are rounded and malleable in appearance. There are no untarnished Joseite-B crystals on this sample. A small 1 mm mass in the Hedleyite has tarnished to a reddish brown, distinctly different than the pinkish Bismuth tarnish. It is possibly Maldonite (Au2Bi), which has been reported in this paragenesis. Thompson (Cdn Min, 1949) in his survey of Canadian telluride occurrences says Joseite tarnishes lead grey and Hedleyite tarnishes iron black. He has four chemical analyses of Hedleyite. His description is at odds with the Mineratlas photo of a purple tarnished Hedleyite. Thompson has Native Bismuth associated with the tellurides so the pinkish tarnished phase fits the paragenesis. There is a tarnished purple trigonal crystal embedded in one of the transparent euhedral Quartz crystals that may be euhedral Hedleyite.

The RRUFF Hedleyite sample from the Good Hope Mine has iron black tarnish on a darker reflective body. It has been identified by single crystals XRD at RRUFF, but has no chemistry. It has also been confirmed by Bart Cannon, according to the collection card. There are no secondary minerals associated with this sample, which are disseminated single Hedleyite crystals in Quartz. The greenish secondary phase forms intergrown, slightly rhombic crystals as solid crusts. In cross section the crust is almost black-green in colour. It forms most thickly directly on the edge of the altering Hedleyite crystals. A much smaller amount of light blue, powdery phase is associated with the green phase. It forms acicular crystals on the Quartz vug in sample (a). There are no secondary minerals listed in the B.C. Minfile entry or the Mindat.org entry for this mine so there may never have been determinations. The closest in appearance to these crystals is Jensenite but it has never been described from Canada. It will take XRD to determine these phases. Dave Joyce in a recent website says that Joseite-b and Hedleyite both occur at the Good Hope Mine at Hedley and they had to microprobe the samples in order to determine which species was present. His samples look very much the same as these and he has Gold associated with Joseite (less tarnished) and Hedleyite (purple tarnished) plates. Mineralatlas has a photo of purple tarnished Hedleyite in Quartz from the Good Hope Mine that is almost identical.

Nickel Plate Mine;

A gold-bearing skarn deposit on a mountaintop 2 kms east of Hedley, north Highway 3 in southwest B.C. British Columbia’s Minfile has an entry on the Nickel Plate Mine which contains: Grain boundary relationships suggest the following three stages of sulphide deposition: (1) pyrite; (2) arsenopyrite and gersdorffite; and (3) pyrrhotite, chalcopyrite and sphalerite. Gold mineralization is related to the latter two stages, and minor amounts of magnetite are associated with the first and last sulphide phases. Pyrrhotite and arsenopyrite are the most common sulphides. Present in lesser amounts, but locally dominant, are pyrite, chalcopyrite, and cadmium-rich sphalerite with minor amounts of magnetite and cobalt minerals. Trace minerals include galena, native bismuth, gold, electrum, tetrahedrite, native copper, gersdorffite, marcasite, molybdenite, titanite, bismuth tellurides (hedleyite, tetradymite), cobaltite, erythrite, pyrargyrite and breithauptite. Trace amounts of maldonite have recently been identified. The native gold, with hedleyite, occurs as minute blebs, generally less than 25 microns in size, within and adjacent to grains of arsenopyrite and gersdorffite.

Several rare-mineral websites carry samples of Hedleyite. A photo on one is almost identical to this sample and says the sample contains yellow tarnished flakes of Hedleyite and bright flakes of Joseite A with quartz and amphibole. Excalibur Minerals has a sample of Hedleyite from a skarn prospect pit of the Good Hope Group, 6 kms SE of Hedley B.C. The sample contains flattened silvery metallic masses scattered in greenish skarn matrix with minor Bi and other minerals.

The original description of Hedleyite (Warren and Peacock,1945) says: Hedleyite is associated with native bismuth, joseite, pyrrhotite, arsenopyrite, calcite, and gold. Bismuth is conspicuous in some samples but joseite cannot be distinguished from hedleyite by inspection. Pyrrhotite and arsenopyrite in small amounts occur in the skarn near the quartz veins. Calcite is sporadically scattered through the veins and stringers. Visible gold occurs close to the bismuth minerals, sometimes as films in the foliated tellurides. The ore minerals are notably poor in sulphur and thus it is evident that the mineralizing solution was deficient in sulphur. The presence of occasional quartz crystals projecting into cavities in the gangue indicate that the temperature of mineralization was low to moderate. There was no indication of secondary minerals in the article but the samples were sent from the mine manager and was not collected by the author.

David Joyce has a suite of samples from the Nickel Plate Mine containing coarse Gold, Hedleyite and Joseite in Quartz. His microprobe study has ascertained which tellurides were which in his particular samples. He does not say whether the results of his study are applicable to the Nickel Plate tellurides as a whole. If the Thompson data is applicable to the weathered samples then the alteration coatings should tell the telluride minerals apart, as each location in the collection has a distinctly different tarnish on the Bi-Te minerals. The 1996 Geology of Canadian Mineral Deposit Types says that the deposit is layers of garnet and pyroxene-rich skarns mineralized with: Gold together with arsenopyrite, pyrrhotite and pyrite together with anomalous Bi-Te-Co is concentrated in the latest stage, a retrograde quartz-calcite-epidote-sulphide assemblage deposited near the skarn-marble boundary. The article says there is no significant Cu in these skarns but Mindat.org has Chalcopyrite at Nickel Plate. A cross-section of the Nickel Plate deposit illustrates the garnet:pyroxene ratio and the Au>3 g/t + Bi, Te, As, Fe limit (probably the grade cut-off) with a cross section of the open pit. A map of the immediate mine area shows the open pits in relation to the intrusions and the Hedley Formation limestones.

Harrison Lake Area:

Several small gold and base metal deposits in the Harrison Lake area, on the north side of the Fraser River in the eastern Fraser Valley, have Bi-Te mineralization. The most abundant Bi-Te mineralization occurs in the Bear Lake Gold deposit.

Bear Lake Mine;

A small, abandoned gold mine on Bear Mountain, near Harrison Hot Springs, has produced bismuth tellurides from low-temperature epithermal adularia veins. The article from the B.C. Government report on Gold Mines in Southern B.C. gives descriptions of the ABO and adjacent Bear Lake deposits. The Mindat.org mineral photographs from this locality are an almost perfect match for Image 5 and there is not another property in the area that is close to the same appearance.

The sample for Image 5 has abundant small plates of tellurobismuthite. Mindat.org’s locality page for the Bear Lake deposit indicates that analyses of the Bi-Te phase by the British Museum resulted in the samples being tellurobismuthite rather than rucklidgeite. Sophisticated structural and chemical analyses are required to distinguish between the two minerals.

Arsenopyrite from the Bear Lake mine is associated with tellurobismuthite. A photo illustrates the calcite-filled veinlets.

Image 5 Arsenopyrite Crystals, Bear Lake Mine

Photos on Mindat.org of the suite of minerals from the Bear Lake Mine make this the proper location for the sample. The constant interpenetrating twins of the Arsenopyrite match the Mindat.org posted photo from here as well. The sample is described as 3” mass of quartz and adularia with arsenopyrite twins to 1mm on white adularia with a scattering of light brown 1 mm ferro-axinite crystals. Photographs from the Bear Lake mine on Mindat.org of the arsenopyrite and ferro-axinite are almost identical to this sample. The sample was originally encased in calcite that was partially etched away with HCl to reveal the crystals. 1 mm platy metallic tellurobismuthite crystals occur embedded in quartz on the back of the sample. This is the occurrence of the phase in the literature. Mindat.org’s locality page indicates that over 100 of these samples were analyzed by the British Museum and a suite of them were analyzed by Josef Vadjak and all were tellurobismuthinite with some variability along the {0001} axis but not across the basal plane.

One pocket has a skeletal platy mass resembling the other BiTe minerals too closely to be anything else. The tarnish is a distinct iron black colour, different from the other British Columbia BiTe minerals. The website from David Joyce has almost identical samples. He says that they have been identified as tellurobismuthite but the BiTe minerals can form oriented intergrowths so the identity of these samples may not be simple.

The tellurobismuthite Joyce has is in plates associated with native gold. pyrite and pyrrhotite occur in lesser amounts and there is tarnished tellurobismuthite associated with the anhedral pyrrhotite. The tellurobismuthite occurs as soft looking; platy masses directly associated with the pyrrhotite, as well as the free crystals in the vug and 1 mm metallic soft plates in massive adularia. I have not scratched any of them to see if they are softer than the arsenopyrite; however all of the other arsenopyrite on the sample occurs in euhedral crystals and not as masses. One photo in the Mindat.org posting has light brown titanite as part of the paragenesis and there is a group of light brown titanite crystals in the cavity with pyrrhotite and arsenopyrite.


Smithers-Terrace Area:

The main occurrence of bismuth tellurides in the Smithers-Terrace area of north-central British Columbia is at the Glacier Gulch prospect. This prospect has had a considerable amount of mineralogical investigation.

Glacier Gulch:

Glacier Gulch is a small gold deposit in silicified tuff sampled by a prospecting trench. It was never large enough to be in production. The trench occurs in a very steep ravine at the mouth of the Kathleen Glacier. A monograph of the prospect is on file. Glacier Gulch is a popular recreational and tourist destination in the Smithers area and there are several photos of Glacier Gulch on the local tourist websites. A 2005 geological report on the Yorke-Hardy molybdenum deposits describes the local alteration patterns but does not mention this occurrence in detail. The mine (prospecting trench) is mentioned in the Mineralogical Record article on the Mineral Occurrences of Western Canada, v. 15 no. 2 (Ingelson, 1984). The B.C. Minfile does not have a listing for this locality, though Mindat.org does. It has a photo of a Joseite sample almost identical to this one. Scott (1971) has a section on Glacier Gulch. He says that joseite 1 (later A) is the main telluride mineral here and the only one in large, single crystal plates.

There have been many samples for sale from Glacier Gulch; all are virtually identical in appearance. The concentration of Joseite on the top of this sample is unusually rich as most of the samples have much larger matrix with a few Joseite grains, normally perpendicular to the perfect cleavage on the sample, scattered through the matrix. The good tetradymite-group mirror cleavage requires the Joseite grains to be at a certain angle to the sample. Both photographs of the Joseite in Mindat.org do not have the same grain size or show the characteristic cleavage.

Thompson (1949) says: In Canada the occurrence of joseite B has been confirmed in British Columbia at Glacier Gulch, Hudson Bay Mountain, near Smithers, where it is associated with bismuth and joseite A; and at the Good Hope mineral claim, near Hedley, Osoyoos Mining Division, where it occurs as coarse plates often intergrown with native bismuth and associated with hedleyite, pyrrhotite, arsenopyrite, molybdenite, and gold, in quartz and skarn.

A sample of Joseite in altered granite is:

Image 6 Joseite, Glacier Gulch, British Columbia

The sample is described as 4 cm x 2 cm x 2 cm mass of silicified tuff with many flattened, metallic 2 mm crystals of joseite, with the mirror-bright reflectance that characterizes the bismuth tellurides. The crystals tarnish to a brassy gold colour on non-cleaved surfaces. There are needles of clear, light brown bismuthinite lining a fracture surface. This seems very unusual for bismuthinite as these needles are not metallic. Thompson (Can Min 1949) in his survey of Canadian telluride occurrences says that joseite (A) is the major mineral here, in plates ½” wide and 2” long. joseite (B) is rare and only occurs as an intergrowth with joseite (A).

B. C. Minfile says: Mineralization occurs along sheared and altered zones in massive, finely crystalline tuffs within the Lower Jurassic Hazelton Group volcanics. Several small showings carrying auriferous tetradymite in shears and quartz veins were mapped and sampled. The host rock is comprised of massive silicified andesite and dark grey to black andesitic tuff which is sheared and folded. Quarrying operations have exposed visible gold and crystals of tetradymite within quartz veins. Minor amounts of erythrite (cobalt bloom) were noted on the quarry face. Large garnet crystals were also noted near the quartz veining. Assay results indicate the presence of high gold, silver, and some platinum associated with the bismuth-telluride deposits. The tetradymite occurs along the planes of shearing and is usually accompanied by native gold. Most of the shears parallel the bedding planes and were produced during folding. These strike southeast dipping between 20 to 40 degrees to the southwest in the lower mineralized zone while the upper and more eastern zones strike south and dip 20 degrees east. The productive zones are mainly confined to the crest of an anticlinal fold with a near vertical axial plane and trends in a southwest direction.

In some instances the mineralization appears to have filled pre-existing fractures due to a well-developed "comb-structure" comprised of quartz crystals of appreciable size formed together with tetradymite crystals. In some cases the tetradymite shows a tendency to assume pseudomorphic (sic) form after quartz.

The Dakota Matrix website, Feb. 24, 2005, has a similar joseite sample, almost identical to this one; however there is no indication as to whether it represents joseite (A) or joseite (B). The website has a notation of bismuthinite for the clear, brown needles, as well as a suggestion that the bismuthinite may be an alteration of the joseite. Given that the bismuthinite needles on this sample form in small vugs next to the embedded joseite this seems reasonable. The Thompson article establishes the preponderance of joseite (A) here.

Vancouver Island:

Bismuth tellurides occur in the Tertiary Age Au mineralization on Vancouver Island. Not all of the occurrences are economic but most contain native arsenic associated with minor gold-cobalt and bismuth tellurides. The better researched localities are: Merry Widow Mine, near Campbell River; the Mount Washington Mine near Comox and small deposits on Texada Island, off the east coast of Vancouver Island.

Merry Widow Mine:

Tellurobismuthite occurs at the Merry Widow Mine, near Campbell River, Vancouver Island. (B.C. Minfile database). It is associated as 1 mm plates with the native arsenic-lollingite-calcite-cobaltite-gold paragenesis that is a Tertiary overprint on the Merry Widow iron-copper skarn mineralization. The Tertiary mineralization at the Merry Widow Mine has also been described in the B.C. Rockhound magazine (Laird 2006) who mentions the presence of tellurobismuthinite (sic).

The Tertiary Age mineralization at the Merry Widow Mine includes native arsenic that is described as 4 cm x 4 cm x 3 cm mass of botryoidal grey native arsenic with a white coating of arsenolite (white powder and small druses of colourless octahedral crystals), claudetite (prismatic colourless prisms like gypsum) and scorodite (olive green; massive). The botryoids of native arsenic appears to have grown on colourless calcite crystals. 1 mm very reflective plates of lollingite occur embedded on the surface of the calcite crystals on the base of the sample. No other matrix is associated with this sample, which appears to be floater in the late As-Au-Co veins in the Merry Widow Mine. Small (< 1mm) lollingite crystals occur on the arsenolite and scorodite. There is a 1 mm thick parallel growth of non-darkening bladed crystals at the base of the botryoids that has evident cleavage.

The Merry Widow Mine is a past producing iron skarn with minor cobalt mineralization. The Minefile database has “Small amounts of arsenopyrite with pyrrhotite, sphalerite, marcasite, cuprite, chalcopyrite and calcite are reported. A north striking fault south of the open pit hosts small amounts of iron and copper sulphides and cobaltite with cobalt bloom (erythrite). Minor pyrite, chalcopyrite and pyrrhotite accompanied by quartz are present”. Jefferey (Minister of Mines Annual Report 1960, page 97) believes: this latter mineralization to be later than the magnetite, and that the orebody is the result of successive mineralizing periods of silicates (skarn), oxides, sulphides and carbonate emplacement.

Commercial ore has developed where the intrusive contact has locally the lowest dip, and where the bulge in the intrusion has caused a change in the strike of the layered rocks. In addition, northeast striking faults are believed to localize mineralization. The Tertiary arsenic mineralization from localities on Vancouver Island and the Queen Charlotte Islands is very similar so any mineral described from one locality may be present in the others. Native arsenic is noted from the Port Alberni area of Vancouver Island by David Joyce but without a mine designation. A 1989 B.C. government report on the Merry Widow Mine lists the features of a copper-iron skarn in detail. The sulphides in this deposit form in a matrix of fine-grained actinolite and calcite associated with fractures perpendicular to faults.

Jim Laird authored a detailed article on the Merry Widow Mine in the Fall 2006 B.C. Rockhound magazine, with a reprint on his website. It says: Minerals of note in the Merry Widow Mine area include; magnetite, colloform magnetite, pyrite, marcasite, chalcopyrite, pyrrhotite, sphalerite, cobaltite, native gold, arsenopyrite, tellurobismuthinite, native arsenic, malachite, erythrite, annabergite, realgar, scorodite, andradite-grossularite garnet, calcite, actinolite, diopside, chlorite, quartz crystal, epidote, and many others. According to Jim (pers. comm.2006) a fault zone running through the cobalt skarn has realgar on the edges and native arsenic in the center. Jim did not sort out the mineralogy of the altering botryoidal native arsenic masses. No photos of the bismuth tellurides are available. The Hudson (2008) Gold, Gemstones & Mineral Sites Vancouver, Vancouver Island entry describes the Merry Widow Mine locality in brief.

I spoke to Jim at the 2008 B.C. Federation show about the locality he said that no one he knows has investigated the secondary arsenic minerals or the bismuth tellurides. He removed a large native arsenic sample, close to a meter across, from the vein. It has gone to the ROM Collection. He did not say whether the secondary minerals had been cleaned from that sample so there may be more mineralogical data to come.

Mount Washington Mine:

A porphyry copper-molybdenum-gold deposit reported to have minor wehrlite by Ingelson (1984). This is a complex deposit with breccia zones and gold-quartz +/- native arsenic/realgar veins. Not much mineralogy has been completed on the deposit but it is the type locality for pararealgar (Roberts et al. (1980). No photographs of the bismuth tellurides are available. The Au-As mineralization is very similar to the Merry Widow Mine and occasionally native arsenic samples from Mount Washington will appear on the mineral market. There are no bismuth tellurides reported from the Mount Washington Mine in Mindat.org but the investigation may be incomplete.

Texada Island:

A series of copper-gold skarns on Texada Island, on the east side of Vancouver Island, have been mined in the early part of the 20th Century. An M.Sc. Thesis (DeLeen, 1946) on the geology of the Little Billy Mine has an investigation of 20 micron wide wehrlite-hessite inclusions in chalcopyrite and bornite. The tellurides are mentioned, but not investigated, in later work on the Texada Island deposits by the B.C. Minfile database and the British Columbia Geological Survey and the telluride is mentioned as wehrlite by Traill (1980). This was prior to the discreditation of wehrlite in 1982 but no modern published work has been done to characterize the telluride inclusions. All of the photographs in the thesis illustrate anhedral inclusions of wehrlite, sometimes associated with hessite and/or native silver, in bornite.
Southeastern British Columbia:

A few gold prospects have been noted to contain elevated bismuth but most have not been mineralogically investigated in detail. Two that have some data are: the CLY Prospect and the Liddell Creek Prospect. There are probably other occurrences of bismuth tellurides in the area that do not have published data. Bismuth tellurides were seldom noted in the early days of gold mining so most of the data has come from post 1965 evaluations.

CLY Prospect:

The gold prospect occurs approximately midway between Salmo and Nelway in south central British Columbia. The deposit has been described in an abstract for the 2007 Denver GSA Meeting, (Howard, 2007). He says that the bismuth minerals occur as droplets of solidified melt consisting of native bismuth-bismuth (sulpho)tellurides-bismuthinite. The bismuth tellurides are: hedleyite, joseite A and B and ingoldite. The veins are in a shallow epithermal environment. No photographs of the bismuth tellurides are available.

Liddell Creek:

This is an unusual locality because it is mentioned in Dana V. II and the Manual of Mineralogy as a locality for tetradymite but it is not mentioned in Walker (1945) or in the British Columbia Minfile database. There is a composition from “Liddle or Lyle (?) Creek” quoted in Traill (1980) (from Maxwell (1965)) with: S 4.30%; Ag 0.91%; Pb 3.50%; Bi 51.85%; Te 36.01% and quartz 3.52% for a Total of 100.09%. This is an impure bismuth telluride but it is difficult to tell how close to tetradymite it is. It is possible it is related to the CLY Prospect under a different name.

Conclusions:

Bismuth tellurides are fairly common minerals in orogenic gold veins and skarns similar to those in British Columbia. They have been noted from the early development of the gold deposits and these deposits have been the subject of active mineral exploration so most outcropping deposits have been located. The mineralogical distinctions within the bismuth tellurides are not often investigated so the database for British Columbia has several localities of generic “bismuth tellurides”. Native tellurium is present in British Columbia but at fewer localities.

Two significant problems occur with the bismuth tellurides are: 1) all of the different phases are platy metallic crystals with excellent basal cleavage so it would require modern microprobe and XRD to distinguish them; 2) there are several deposits with 2 to 3 co-existing bismuth telluride phases so not all of the phases can be characterized by a single set of analyses. These co-existing phases can occur as intergrown single crystals and thus give non-stoichiometric results from chemical analysis alone. Tarnish can be used in some cases to distinguish co-existing phases from the same deposit but it is not well enough understood to use tarnish to distinguish an unknown bismuth telluride phase.

The bismuth tellurides were often an afterthought in the pursuit of gold-silver deposits because until recently bismuth and tellurium had limited markets and so was not sought as minable commodities. The use of tellurium in high-tech applications has led to a renewed interest in tellurium mineralization. Deposits such as the White Elephant Mine that were of marginal economic value for its contained gold content might be re-evaluated as a source of tellurium metal. Tellurium has in the past been a by-product metal produced by smelting polymetallic ores such as those of the Sullivan Mine, where it does not occur as separate Bi-Te minerals.

The use of tellurium and bismuth in the geochemical exploration for buried gold deposits may allow the delineation of other bismuth telluride deposits if the geochemical anomalies are followed up with other mineralogical investigations. In most published reports the geochemical data is listed by chemistry alone without any mineralogical follow-up.

Modern analytical techniques are useful in distinguishing the bismuth telluride minerals when chemistry alone is not definitive. Overgrowths and intergrowths of two or more bismuth telluride phases are a common occurrence and can only be distinguished by microprobe and elemental mapping. The difference in atomic weight between Te (127.6) and Pb (207.2) allow for the discrimination of Pb/Te ratios in backscatter images by difference in the grey scale. Any S-bearing phase (atomic weight S is 32.07) will have a lower grey scale.

The collecting potential for the bismuth tellurides is fairly high as there are a number of small gold showings that have been abandoned and the quartz veins containing bismuth minerals will be notable on the dumps. Rare mineral collecting in British Columbia has been sporadic with many localities not being visited and few instances of systematic collecting at any locality.


References:

Thompson (1951) Mineral Occurrences in Western Canada; American Mineralogist v. 5 pt. 3 p. 504-508

Scott J.D. (1971) Collecting Rare Sulphosalts in British Columbia; Mineralogical Record v. 2 no.5 p. 203-209

Traill R. J. (1980) Catalogue of Canadian Minerals; Geological Survey of Canada: Paper 80-18, 432 p.

Tomkins A.G., Pattison D.R.M. and Frost B.R. (2006) On the Initiation of Metamorphic Sulfide Anatexis: Journal of Petrology v. 48, no. 3 pp. 511-535

Gagne S., Beaumont-Smith C.J., Williams-Jones A.E. and Hynes A. (2007) Investigation of a Pb-Ag-Au-rich hangingwall in Lens 4of the Chisel North Mine, Snow Lake, Manitoba (NTS 63K16): preliminary results: Report of Activities 2007, Manitoba Science, Technology, Energy and Mines, Manitoba Geological Survey p. 43-50

Cook N.J., Ciobanu C.L., Spry P.G. and Voudouris P. (2009) Understanding Gold-(Silver)-Telluride-(Selenide) Mineral Deposits; Episodes, V. 32, No.4, pp. 249-263

Henley R.W, Maviogene S.J. and Tanner D. (2012) Sulphosalt Melts and Heavy Metal (As-Sb-Bi-Sn-Pb-Tl) Fractionation during Volcanic Gas Expansion in the El Indio, Chile Paleofumerole; Geofluids, v. 12, Issue 3, p. 199-215

Ray G.F. (2013) A review of skarns in the Canadian Cordillera; British Columbia Geological Survey Open File 2013-08; 50 p.

Duff S. (2016) Ore Types of the Auriferous Lalor VMS Deposit, Snow Lake, Manitoba: Implications for Genesis and Post Depositional Processes: M.Sc. Thesis, University of Ottawa, 123p.

Viketeva O.V., Prokofiev V.Y., Gamanin G.N. Giryachev N.A. and Bortnikov N.S. (2018) Intrusion-related gold-bismuith deposits of North-East Russia: PTX parameters and source of hydrothermal fluids: Ore Geology Review , v. 102, p. 240-259

Groves D.L., Santosh M., Deng G., Wang Q., Liqiang Y. and Zhang L. (2019) A holistic model for the origin of orogenic gold deposits and its implications for exploration: Mineralien Deposita, June 2019, p. 1-18.




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Discuss this Article

6th Aug 2019 01:05 UTCKeith Compton Manager

Great article Richard

I'm sure that there are are hundreds/thousands of gold deposits which would yield many of these minerals world-wide. If only we cared to analyse them and seek them out.

6th Aug 2019 15:19 UTCRichard Gunter Expert

Hi Keith:

Thank you for the compliment. Bismuth tellurides are not as common in gold deposits as I thought at first; that was one of my reasons for doing the article.

14th Sep 2019 07:38 UTCAlfredo Petrov Manager

Thank you, Richard. Very interesting. I have a few Bi tellurides from B.C. and had long wondered how accurate the IDs were.
Looking forward to your next article.

15th Sep 2019 18:38 UTCRichard Gunter Expert

Hi Alfredo:

Thanks for the compliment. As you can see by my article it depends on what locality your Bi tellurides come from. Some localities like the White Elephant Mine have a fairly simple Bi-Te mineralogy and so the species designation is straight forward. Glacier Gulch seems to be similar. The Bi-Ti species from the Hedley area are much more complex and intergrown; thus needing more analyses.

I am working on an update to the 1992 Mineralogical Record Special Issue on the Yukon phosphates. There is a lot of data that has been published since 1992 and many new parageneses have been found.

Richard

8th Nov 2019 16:37 UTCRoss Gussen

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Richard Gunther
Thanks for the article on "Bismuth Tellurides in British Columbia" having been to several of these sites, it struck a cord. I was employed by Canadian Johns Manville, as part of a geological survey team in the late 60's. We were primarily interested in locating possible porphry copper/molybdenite deposits (Brenda/Lornex). But would recon other types of mineral occurrences brought to our attention, the White Elephant being one. Lately Bear Mountain has provided a number of interesting specimens, I have attached a image of what I thought was rucklidgeite, but after reading your article, feel more comfortable tentatively labeling it as tellurobismuthinite. I still hope to read a knowledgeable and informative article on the metamorphosed Devonian Permian limestone contact with a tertiary granodiorite located at the southern most portion of Bear Mountain and Seabird Island.
Ross Gussen

8th Nov 2019 21:03 UTCRichard Gunter Expert

Hi Ross:

It appears that tellurobismuthite is the major Bi-Te phase at Bear Mountain. Have you seen the data on the Mount Breakenridge area?  It is as close to Bear Mountain as I have seen.
 
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