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The Logtung tungsten-molybdenum deposit is located in Yukon Territory, immediately north of the British Columbia boundary, about 163 kilometres west of Watson Lake, and 205 kilometres east-southeast of Whitehorse, in the Watson Lake Mining District. The main deposit is located in Yukon, but the mineralized system extends southward into British Columbia, where the occurrence is known as NORTHERN DANCER or LOGTUNG, B.C. Minfile number 104O 06.

The deposit and surrounding geology are well described on the Yukon Minfile page, as follows:

“The property is located in south-central Yukon near the border with British Columbia. Recent geological mapping completed by geologists employed by the Ancient Pacific Margin NATMAP project; a projected jointly funded by the Geological Survey of Canada, the British Columbia Geological Survey and the Yukon Geology Program shows the area is underlain by mafic to intermediate volcanic and epiclastic rocks assigned to the Klinkit Succession. Recent age dating by Mortensen and Gabites (2002) has resulted in a Pennsylvanian age for the Klinkit Succession. Roots and [sic] et al. [date?], have recently assigned the Klinkit Succession to the Yukon-Tanana terrane.

The Klinkit Succession is intruded by a Triassic diorite stock flanked by numerous satellite dikes and a mid-Cretaceous monzonite stock accompanied by pegmatitic dike swarms and a slightly younger but apparently comagmatic felsic dike complex. Both ages of intrusions produced extensive hornfels halos and localized skarn horizons. Mineralization is hosted by an extensive, multi-episode vein system that is enriched in several metals, most notably tungsten and molybdenum. The vein system is centred on the felsic dike complex, and approximately 95% of the mineralization occurs within veins and fractures with the remainder found as disseminations within the felsic dike complex and skarn horizons. The veins crosscut all units and are believed to be genetically related to emplacement of the felsic dike complex.

The original mineralized showing found by the GSC consisted of blades of wolframite with purple fluorite, tourmaline, cosalite and beryl in a quartz vein cutting quartz monzonite. The main zone found nearby in 1976 consists of scheelite and molybdenite in a multi-stage stockwork vein system developed in a quartz porphyry plug, and disseminated in a vein stockwork which cuts garnet-diopside skarn and hornfels peripheral to a fluorite-rich quartz monzonite stock which intrudes cherty banded argillite and quartzite of Pennsylvanian age.

Mineralization is controlled by four overprinting stages of veining: (Type 1) quartz-molybdoscheelite veins occurring up to 1.5 km away from the western edge of the monzogranite, but most well developed in calc-silicate rocks near the felsic dike complex at the north flank of the main stock; (Type 2) quartz-pyrite-scheelite proximal to felsic dikes; (3) quartz-moly in and near the felsic dikes; and (4) polymetallic sheeted veins.

Studies by Noble, Spooner & Harris [1984] suggest that this deposit has many similarities to classic porphyry Mo deposits and that the skarn minerals are incidental to the W-Mo mineralization, which is almost totally confined to porphyry-style crackle breccia.”

Giles Peatfield comments:

Logtung is a large tungsten-molybdenum deposit that is still in the exploration and development stage. AMC Mining Consultants (Canada) Ltd. prepared a “Preliminary Economic Assessment” on behalf of Largo Resources Limited, effective 28 March 2011 (Molavi et al. 2011). The estimate adhered to guidelines set forth by National Instrument 43-101 and the CIM Best Practices and Definition Standards. The combined measured and indicated resource was given as 223.4 million tonnes grading 0.102% WO3 and 0.029% Mo, with an additional inferred resource of 201.2 million tonnes grading 0.089% WO3 and 0.024% Mo. The report, to which interested readers are referred, contains much more detail.

There are numerous radiometric age determinations available for the rocks and mineralization on the property. As noted above, Mortensen and Gabites (2002) have assigned a Pennsylvanian age to the regional volcano-sedimentary rocks. Also as noted above, Yukon Minfile states that these strata are intruded by a Triassic diorite stock. However, Brand (2008) gave a Pb/U age on zircons from the diorite in the Yukon portion of the property as 187.7±2.6 Ma (million years before present). There are numerous age determinations for rocks directly associated with the Mo/W mineralization, done by various methods, ranging from an Ar/Ar age of 106.2±0.8 Ma on muscovite from skarn (Joyce et al. 2015) to as old as 118±2 Ma by Rb/Sr whole-rock on monzogranite (Stewart, 1983 quoted in Noble et al., 1984). This last age was re-calculated by Brietsprecher and Mortensen as 117.6±3.5 Ma. Brand (2008, personal communication from Drs. Craig Hart of the Yukon Geological Survey and David Selby of Durham University in 2006) quoted a Re-Os age on molybdenite as approximately 108 Ma. Hunt and Roddick (1987) quoted a K/Ar date on muscovite from a quartz-vein stockwork of 109±2 Ma. Two outliers of interest are an Ar/Ar age of 85.3±0.6 Ma on feldspar from a beryl-bearing pegmatite (Joyce et al. 2015), and a U-Pb age on zircons from a monzogranite of 58.0±6.4 (Mihalynuk and Heaman, 2002) – this last age is regarded by other workers as not valid. In summary, Pennsylvanian volcano-sedimentary strata are intruded by an Early Jurassic diorite pluton, which is in turn intruded by several acid intrusive rocks with apparently coeval Mo/W mineralization of generally Early Cretaceous age.

Comments on the minerals reported:

With a few exceptions, the identification of the minerals listed are from the work of Noble et al. (1984) and Brand (2008). Seven tentative identifications are for minerals inferred to be present, based on the results of Rietveld analyses reported in Brand (2008). It is appropriate to note that Brand’s work was an exhaustive treatment of the mineralogy of the deposit and surrounding rocks. Note also that ‘Northern Dancer’ is an alternative name for ‘Logtung’.

In the following descriptions, there are references to various vein types. These are listed below in order of decreasing age; the minerals listed are the characteristic ones for each type – several other minerals may be present:
Type 1 veins: quartz-molybdoscheelite
Type 2 veins: quartz-pyrite-scheelite
Type 3 veins: quartz-molybdenite
Type 4 veins: polymetallic sheeted – quartz-beryl-scheelite-molybdenite

Actinolite?: Inferred, based on Rietveld analysis of calc-silicate rocks and hornfels. Brand (2008) commented “Please note that ‘actinolite’ could actually be amphibole, and possibly hornblende, as their structures are very similar (site occupancies were refined to reflect the phase composition as closely as possible).”

Allanite: Noble et al. (1984) wrote that “Accessory primary minerals include fluorite and scheelite as well as ilmenite, magnetite, pyrite, zircon, allanite, and apatite.” Brand (2008) gave more detail, writing that “Allanite is very rare in the Northern Dancer system, and only two examples were found in the representative sample set. A small, fine-grained aggregate mass was found in the groundmass of the felsic porphyry dikes (sample Al-06-06), and another example was found in a thin Type 2 quartz-pyrite-scheelite vein in fine-grained garnet-pyroxene skarn (QSM-27). This second grain contained euhedral growth zones based on varying Ce-La content . . . . EDS analysis via the SEM showed the Ce-La content increases outward from the core/origin. It occurs in an epidote-rich Type 2 vein, and is associated with pyrite, chalcopyrite, fluorite, and clinopyroxene.”

Apatite: Brand (2008) wrote that “Apatite is a ubiquitous, if fine-grained, accessory mineral at Northern Dancer. It is never visible in outcrop and crystals are always less than 1 mm in diameter. It can occur in every rock unit, and is found in most vein alteration haloes, but it is most abundant in thick Type 4 veins and in zones of silica alteration or ‘brain rock’.”; and added that “One hundred and fifteen electron microprobe analyses were obtained from 24 apatite crystals/grains in five different polished sections and nine different vein/host environments.”; and further stated that “Apatite at Northern Dancer is rich in fluorine, characterizing them [sic] as fluorapatite; the deposit-wide average is 4.15 wt.% F.”

Arsenopyrite: Noble et al. (1984), describing veins to the north-east of the main deposit, wrote that “These veins show a well-developed internal zonation with sphalerite and arsenopyrite typically occurring along vein walls and sphalerite, galena, galenobismutite . . . , and pyrrhotite in the vein interiors. Vein cores are dominated by quartz, calcite, and chlorite. Accessory minerals include löllingite . . . and stannite. The latter is an interesting accessory to be associated with W and Mo, and accounts for grades of up to 0.1 percent Sn which were recorded by Mulligan (1975, table1). The veins also run at typical, marginally economic Ag grades.”

Beryl: Mulligan (1968) reported that “This locality [Logjam Creek] is immediately south of the Wolf Lake area, Yukon territory, and was reported by W. H. Poole (personal communication). Beryl is present as small, poorly formed, rather opaque, bluish green crystals and shapeless masses. One specimen of granite contains a stringer about 2 inches long by nearly an inch wide composed mostly of beryl; some beryl is also visible in specimens of quartz.” Brand (2008) added considerable detail, writing in part that “Beryl occurs in Type 4 veins, in both the central zone of polymetallic sheeted veins (quartz-beryl-scheelite-molybdenite veins), and distal beryl-wolframite sheeted veins to the southwest. Type 4 veins in calc-silicate and hornfels host rocks contain more beryl than felsic dike hosted veins; however beryl occurs consistently throughout the deposit and at depth. It is usually blue or rarely blue-green in colour, and averages 1-3 mm wide but euhedral crystals occur up to 4.2 cm wide.”

Biotite: Biotite is a common mineral in the rocks and veins of the deposit area. Brand (2008) provided considerable data regarding the compositions of various types of biotite; details of this work are available in her thesis but are beyond the scope of this summary.

Bismuthinite: Noble et al. (1984), describing the mineralogy of the veins in the central zone, wrote that “Accessories include fluorite and bismuthinite.” Brand (2008) expanded on this, writing that “Bismuthinite occurs as an accessory mineral in beryl-wolframite sheeted veins which occur to the southeast, outside the Northern Dancer deposit boundary. However, it has been occasionally noted in drill core from the deposit itself. In one case, it occurs in anhedral masses, associated with calcite, garnet and minor sphalerite, at the wall of a Type 3 vein. It has also been noted as a rare accessory in deeper Type 4 veins, associated with massive chalcopyrite, pyrite, and sphalerite.”

Calcite: Brand (2008) wrote that “Late, barren calcite veins crosscut all vein types including late barren quartz veins, and fill faults and fractures throughout the deposit. Occasionally, fine-grained, bladed chabazite (zeolite) occurs along vein/fracture walls with fine-grained calcite in the cores. These veins occur typically in calc-silicate and hornfels host rocks, and are usually very thin, generally 2 mm or less.”

Chabazite Group: Both Noble et al. (1984) and Brand (2008) mention ‘chabazite’ in passing, in association with calcite, but neither give any specific information.

Chalcopyrite: Brand (2008) wrote that “Chalcopyrite dominantly occurs as an accessory mineral in Type 4 veins, usually with other sulphides, especially pyrite. It may also be present in fractures within altered diorite host rocks, and it is seen disseminated in rusty hornfels (in outcrop) along Logtung Ridge, near the diorite contact with the metasedimentary country rocks. In Type 4 veins, chalcopyrite can occur as separate subhedral grains up to 8 mm across, as blebby inclusions in large pyrite crystals, or as blebs within sphalerite inclusions (also known as ‘chalcopyrite disease’) in pyrite . . . .”

Chamosite?: Inferred, based on Rietveld analysis of altered diorite.

Chlorite Group: Noble et al. (1984) reported ‘chlorite’ as a common accessory and alteration mineral. Brand (2008) wrote that “Hydrous minerals, including phyllosilicates, are relatively rare in most calc-silicate host rocks at Northern Dancer. However, micas do exist in intrusive units, especially the diorite, and chlorite is a minor accessory mineral in several vein/host environments.”; note, however, that she reported peaks in the Rietveld analysis for clinochlore, commenting that “Clinochlore refers to the variety of chlorite found at Northern Dancer.”

Chrysoberyl?: Mulligan (1968), wrote that “A thin section of granite showed abundant quartz, perthitic untwinned potassic feldspar, albite, brown biotite, colourless muscovite, and minor fluorite. No beryl was found, but a few tiny biaxial grains with moderately high relief and birefringence, which might possibly be chrysoberyl, were associated with the black opaque minerals.” No other worker reported chrysoberyl, and it must definitely be regarded as tentative.

Clinopyroxene Subgroup: Noble et al. (1984) reported that “Diorite mineralogy is dominated by plagioclase and hornblende, with lesser amounts of quartz, biotite, clinopyroxene, and K-feldspar.” Brand (2008) has numerous references to clinopyroxene.

var. Diopside: Noble et al. (1984) gave numerous examples of diopside in veins, in calc-silicate rocks, and as an accessory in intrusive rocks. Brand (2008) was less definitive, in many cases referring to diopside and in others to ‘diopside-hedenbergite’; stating that “Most calcic pyroxene in the deposit is Mn-poor, and falls between the diopside and hedenbergite end-members. The most diopside-rich pyroxene end-members at Northern Dancer include: (1) massive pyroxene which occurs in thick, potassium-rich Type 4 veins in hornfels, and (2) in altered/silicified calc-silicate groundmass, associated with fluorite and molybdenite.”; note that all of Brand’s many analyses of clinopyroxene lie below 50% hedenbergite, and could be classified as diopside – this is except for five analyses to be discussed below as johannsenite.

var. Johannsenite: Brand (2008) noted that “Five analyses from polished section QSM-4 have end-member compositions averaging 91.67% johannsenite; these are low iron . . . . These pyroxenes occur as the dominant groundmass component, within silicified calc-silicate host rock
located close to surface (i.e., at a high-level in the deposit), which has been oxidized. However,
garnets in this section have relatively Ca- and Mg-rich compositions, and occur in more garnet
rich calc-silicate zones, and do not host scheelite. Scheelite hosted by johannsenite-rich
pyroxene is high in Mo (6.62-11.65 wt.% MoO3).”

Clinozoisite: Brand (2008) wrote that “Clinozoisite occurs in veins, and is most likely an alteration product of epidote. This is commonly seen in reopened Type 2 veins (by Type 3 or 4 veins), . . . . As such, it can occur with zoned scheelite. It may occur in thicker Type 3 or Type 4 veins, as anhedral masses with fluorite, scheelite, and pyrite. Clinozoisite can also occur in altered, silicified zones of calc-silicate, as seen in Fig. 8.16. Here again, it is likely the alteration product of earlier epidote.”

Cosalite: Mulligan (1968) wrote that “A quartz vein in the granite plug contains a metallic mineral that was identified as cosalite (a Pb Bi sulphide).”

Epidote: Brand (2008) wrote that “Epidote is a significant vein mineral and alteration component at Northern Dancer, as it is one of the few hydrous minerals associated with mineralization. It is dominantly found in the Type 2 veins (quartz-pyrite-scheelite veins), but is also found as a minor component in most other veins.”

Feldspar Group: Feldspars of various types are common at Logtung. Brand (2008) presented a detailed review of the various types; it seems not necessary for this review to go into more details except to quote her summary at length, as follows: “Feldspar is a component of intrusive rocks, metasedimentary host rocks, and veins at Northern Dancer. Both plagioclase and potassium feldspar occur in all intrusive phases, and can be zoned, or show evidence of relict zoning, as in the monzonite . . . . In general, plagioclase is the dominant feldspar in the monzonite, occurring as rims on earlier potassic grains, or as sub-euhedral grains in a coarse-grained matrix. Potassium feldspar dominates the felsic dike phases, especially the ‘brain rock’ unit, occurring as fine-grained, anhedral masses in felsite, as small subhedral grains dispersed through quartz porphyry or as bands in the ‘brain rock’ (between 0.1 mm to several cm wide). Typically, the fine-grained matrix in the felsic dikes is composed of intergrown plagioclase and potassium feldspar. Ca-rich plagioclase and potassium feldspar are both found in the diorite, although the latter is more common. Feldspars, usually potassic, can also occur as very fine-grained, anhedral groundmass components of calc-silicate and hornfels metasedimentary host rocks, or in haloes around veins. Within veins, plagioclase is most occasionally found in vein cores, as fine-grained anhedral masses. Potassium feldspars can occur in the same way, in addition to forming euhedral, compositionally zoned crystals growing perpendicular to Type 4 vein walls In rare cases, Type 4 veins are composed almost entirely of anhedral massive potassium feldspar.” For details of species identified, refer to Brand (2008).

Ferberite-Hübnerite Series: Mulligan (1968), discussing the Logjam Creek area, noted that “A little wolframite was seen.” Noble et al. (1984) noted wolframite in late-stage veins, but did not specify the composition. Brand (2008) had numerous references to wolframite in veins. None of the workers gave any compositional data.

Fluorite: Brand (2008) wrote that “At Northern Dancer, fluorite is ubiquitous throughout the entire system. Three colours of fluorite have been noted in the deposit: grey-colourless (most common), purple (in Type 4 veins), and green (rare). It occurs in the full range of intrusive rocks, veins, and metasedimentary host rocks, as both a primary and as an alteration mineral. Overall, fluorite is regularly associated with scheelite both in earlier and later stage veins throughout the Northern Dancer deposit.”

Galena: See note above for arsenopyrite.

Galenobismutite: See note above for arsenopyrite.

Garnet Group: Garnets are common at Logtung, especially in the skarns. Several varieties have been named. Brand (2008) went into considerable detail, with numerous analyses; writing that “Garnets at Northern Dancer are split into two compositional groups. Within felsic intrusive phases, they fall between spessartine and almandine end-member compositions, whereas in the calcareous metasedimentary rocks, they are ‘grandites’ (between grossular and andradite end-members). End-member compositions are plotted . . . on a ternary of grossular (Gro), andradite (And), and ‘pyralspite’ (Pyr = pyrope + almandine + spessartine). The two compositional groups are clearly distinguished. Based on their host environment, these compositions agree with average end-member proportions reported in the literature; according to Wright (1938), granites/pegmatites are typically spessartine-almandine rich, while calcareous contact rocks are grossular-andradite rich (or ‘grandite’ - there is a complete solid solution between grossular and andradite).” For interest, Grice and Gault (1985) reported “. . . orange-brown grossular crystals a few centimetres across, . . . .”

Graphite: Noble et al. (1984), describing graphitic quartzite, wrote that “In thin section, a planar fabric is defined by a common orientation of lenticular recrystallized quartz grains and surrounding graphite flakes.”

Helvine Group: Noble et al. (1984, 1986) mentioned ‘helvite’ in sheeted quartz-molybdenite veins, but gave no details. Brand (2008) reported ‘helvite-danalite’ in calc-silicate rocks.

Hornblende: Noble et al. (1984) reported hornblende as a rock-forming mineral in diorite and as an alteration product in the selvages of quartz-pyrite-scheelite veins. Brand (2008) presented extensive chemical information for hornblende in various modes of occurrence; this information is beyond the terms of this review, and interested readers are referred to her thesis.

Ilmenite: See note above for allanite.

Kaolinite?: Inferred, based on Rietveld analysis of altered diorite.

Laumontite?: Inferred, based on Rietveld analysis of calc-silicate rock with early-stage mineralized veins.

Löllingite: See note above for arsenopyrite.

Magnetite: Noble et al. (1984), describing the monzogranite, wrote that “Accessory primary minerals include fluorite and scheelite as well as ilmenite, magnetite, pyrite, zircon, allanite, and apatite. Primary scheelite, molybdenite, and uraninite as well as quartz and two feldspars occur
in pegmatitic pods.” Brand (2008) commented that “Magnetite was detected in three samples via X-ray powder diffraction analysis; however, magnetite was not identified in polished section.”

Marcasite: Noble et al. (1984) reported marcasite as an accessory mineral in sheeted quartz-molybdenite [Type 3?, 4?] veins in the central area. Brand (2008) noted marcasite in Type 4 veins.

Molybdenite: This is the only important Mo mineral in the deposit. Brand (2008) described it as follows: “Compositionally, molybdenite is essentially pure at Northern Dancer; aside from minor
impurities such as Fe where molybdenite and pyrite/pyrrhotite are associated (the molybdenite
may contain small pyrite/pyrrhotite inclusions).”

Molybdoscheelite: This is essentially scheelite with an elevated content of MoO3. Brand (2008) analyzed a large number of scheelite grains, and reported MoO3 contents, for 202 grains in Type 1 veins, averaging 4.85 wt % MoO3. Grains in other vein types had much lower MoO3 contents. Molybdoscheelite is not a common tungsten mineral in the deposit.

Monazite: Brand (2008), describing alteration in the monzonite, wrote that “In polished section, fine- grained k-feldspar and albite are intergrown with fluorite. Biotite is Ti-Mn rich and is commonly associated with fine-grained apatite (which can be zoned due to REE content), ilmenite, rutile and zircon. Apatite and ilmenite also occur as inclusions within biotite. Rare monazite and xenotime occur, as well as occasional Nb-rich scheelite intergrown with rutile. These rarer accessory minerals are commonly zoned based on REE content, as seen in backscatter mode on the SEM.”

Muscovite: Noble et al. (1984) noted that “Individual flakes [of molybdenite] in the aggregate are often intergrown with muscovite, particularly in intrusion-hosted veins.”; and further that “Scheelite is typically rimmed by molybdenite flakes and in some cases is sandwiched between flakes of muscovite and molybdenite.” Brand (2008) wrote that “At Northern Dancer, muscovite is found primarily in the felsic dikes and ‘brain rock’ units. Muscovite also occurs in altered monzonite, where it is associated with fluorite and potassium feldspar . . . . It may also occur in zones where Type 4 veins appear to grade into ‘brain rock’ layers or very siliceous zones of porphyry . . . . In these locations, muscovite is associated or intergrown with K-feldspar, either in layers or at what appear to be vein walls or edges of quartz flooding. These muscovite-feldspar layers and “clots” (which can occur as radiating crystals) appear to be traps for scheelite, molybdenite and rutile . . . .”

Native Bismuth?: This mineral probably does not occur at Logtung. It is listed by Mindat, based on a reference to a USGS publication (https://doi.org/10.3133/cir930o). The USGS compiler listed BSMT (bismuth), rather than BSMN (bismuthinite), giving the source reference as Noble et al. (1984). Careful reading of that reference reveals that there are references to bismuthinite, but none to native bismuth. Clearly, the error lies with the USGS compiler.

Prehnite?: Inferred, based on Rietveld analysis of calc-silicate rock with late-stage mineralized veins and altered diorite.

Pyrite: Noble et al. (1984) noted that within the deposit, “Pyrite is the most common sulfide mineral, typically containing blebs of pyrrhotite and chalcopyrite.”

Pyrrhotite: See note above for arsenopyrite.

Quartz: This is ubiquitous, both as a rock-forming mineral and as a constituent of various types of veins.

Rutile: Brand (2008) wrote that “Rutile is relatively rare, and tends to occur in local environments where Ca is low (as high Ca would likely promote titanite development), such as areas of quartz flooding, or in thicker quartz veins within the felsite units. As a result, rutile and titanite do not commonly occur together at Northern Dancer, and overall, titanite is the more dominant Ti-mineral in the system. Rutile can occur in fine-grained, rare, aggregate masses in the monzonite, along with apatite, zircon, biotite, ilmenite, and potassium feldspar . . . . In altered monzonite rocks, the rutile is Nb-rich, and it occurs near scheelite grains which are also Nb-Ta-rich . . . . It can also form in Type 4 veins intergrown with chlorite, alongside euhedral beryl and
molybdenite, . . . .”

Scheelite: Brand (2008) wrote that “Scheelite and/or molybdoscheelite are found in all four mineralized vein types at Northern Dancer, and in various metasedimentary/groundmass environments. Minor dissemination also occurs proximal to the veins, i.e. in their alteration halos. Scheelite morphology, grain size, abundance and composition change by vein/host environment.” She went on to describe the morphology and chemistry of the minerals in much detail; this is beyond the terms of this review, and interested readers are referred to her thesis. Scheelite is the principal tungsten mineral in the deposit.

Sericite: Brand (2008) noted sericite as a common alteration of feldspars.

Siderite?: Inferred, based on Rietveld analysis of wollastonite/vesuvianite veins and hornfels.

Sphalerite: See note above for arsenopyrite.

Stannite: See note above for arsenopyrite. To reiterate, and expand on the stannite report, as Noble et al. (1984) noted in the north-east polymetallic veins “Accessory minerals include löllingite . . . and stannite. The latter is an interesting accessory to be associated with W and Mo, and accounts for grades of up to 0.1 percent Sn which were recorded by Mulligan (1975, table1). There is a potential issue here in that the Mulligan report of 0.1 percent Sn may refer to veins in the nearby Logjam Main mine (Yukon Minfile number 105B 038) rather than to the veins in the Logtung deposit area. However, there is no question that the Noble et al. report of stannite refers to the Logtung veins, although there is no detailed information available regarding their identification of the mineral. Brand (2008) did not mention stannite.

Stilbite?: Inferred, based on Rietveld analysis of calc-silicate rock with early-stage mineralized veins, and altered diorite.

Titanite: This is a common accessory mineral in most rock types on the property; see note above for rutile.

Tourmaline: Mulligan (1968) wrote that “A thin section of a mineralized quartz vein showed fine green tourmaline in a narrow veinlet.” Brand (2008) expanded on this, writing that “Tourmaline is extremely rare within the core of the Northern Dancer deposit; however, black tourmaline can occur within beryl-wolframite sheeted veins extending to the southeast. In one rare example within the deposit, tourmaline occurs in a fine-grained, aggregate mass with fluorite, magnetite, sphalerite, and plagioclase in myrmekitic quartz porphyry, within the felsic dike complex. These grains were too fine-grained to analyze quantitatively, but they did register Mg, Mn, Na, and Fe spectral peaks with EDS analysis (via the SEM). This suggests the species is likely schorl (Fe and Na-rich tourmaline), or less likely, buergerite (an F-rich tourmaline).”

Uraninite: See note above for magnetite.

Vesuvianite: Brand (2008) noted that there are skarns with vesuvianite, wollastonite and often diopside in the deposit area.

Wollastonite: See note above for vesuvianite.

Xenotime: Brand (2008) wrote that “Xenotime is occasionally found in altered monzonite near the contact with the metasedimentary country rocks. Here it can be zoned, HREE- (Y, Yb, Gd, Er, Dy) and LREE rich, and is commonly associated with scheelite, monazite, zircon, and apatite (Fig. 8.29). Minor inclusions in xenotime are LREE-, Th and Nd-rich. Rarely, it is found associated with pyrrhotite and small, Mn-rich garnets in quartz-feldspar porphyry rocks . . . . In quartz-feldspar porphyry rocks, it can occasionally form aggregates with fluorite in the matrix. Due to its minor nature and the difficulty in analyzing for heavy rare earth elements via electron microprobe, xenotime was not analyzed for this study.”

Zircon: See note above for magnetite.

Rock types reported:

The identification of the rocks listed are from the work of Noble et al. (1984) and Brand (2008). For details, refer to these papers.

Research by Giles Peatfield, Courtenay, British Columbia.
Edited by Doug Scott, Ottawa

Posting prepared 11 January, 2026.

Other Databases

Canada Yukon Survey:	105B 039

Other Regions, Features and Areas containing this locality

References

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