Dublin Gulch, Mayo mining district, Yukon, Canadai

Regional Level Types
Dublin Gulch	Gulch
Mayo mining district	Mining District
Yukon	Territory
Canada	Country

The Dublin Gulch area includes gold-scheelite placer deposits along Haggart Creek, and sulfide vein deposits in the surrounding hills. The deposits are described by Boyle (1965).
Further comments by Giles Peatfield for the locality:
Dublin Gulch, with its several “pups”, flows westward to join Haggart Creek, about 48 kilometres north of Mayo, Yukon. It is a long-standing placer stream, in an area with numerous bedrock occurrences of gold, tungsten, tin and base metals (see, e.g.: Yukon “Minfile” listings 106D 021 “Peso”; 106D 025 “Dublin Gulch” or “Eagle”; and 106D 127 “Olive Shamrock”.) The Eagle deposit has recently been put into production as an open-pit, heap leach gold-silver mine (see vitgoldcorp.com for details).
While a student at the University of British Columbia (UBC), R. M. Thompson was attached to the Geological Survey of Canada party headed by H. S. Bostock (see Bostock, 1959), at which time he collected a large sample of jig concentrate from a placer operation, likely the Taylor operation in Dublin Gulch. Later, when he became Professor of Mineralogy at UBC, he assigned this material to a graduate student for detailed mineralogical examination (Tempelman-Kluit, 1963). Tempelman-Kluit was at that time working on his M.A.Sc. Thesis on the Haggart Creek – Dublin Gulch Area (Templeman-Kluit, 1964). His mineralogical examination resulted in the identification of a large number of minerals, as detailed below.
Comments by Giles Peatfield regarding some of the minerals reported. Note that I have chosen to comment on almost all of the minerals present:
Albite: Reported by Aho (1949).
Allanite: Reported by Aho (1949) and X-ray confirmed by Tempelman-Kluit (1963).
Anatase?: Templeman-Kluit (1963) mentioned this as possible in an X-ray pattern for a hematite specimen. It should be regarded as tentative for the locality.
Apatite: Reported only by Templeman-Kluit (1963), as a minor constituent of the concentrate. It should be regarded as valid for the locality.
Arsenopyrite: Reported by Aho (1940) and Templeman-Kluit (1963).
Baryte: Identified by Templeman-Kluit on the basis of a single grain with a specific gravity of 4.47; the grain gave a positive flame test for Ba.
Beudantite: Traill (1970) reported that “Beudantite has been found as a coating on arsenopyrite in heavy mineral concentrates from a placer at Dublin Gulch (X-ray Laboratory, Geol. Surv. Can.).” No further details were given – perhaps this is from the material collected by Thompson in 1943? It was not identified by Tempelman-Kluit (1963).
Biotite?: Templeman-Kluit (1963) found this as a relatively common constituent of the concentrate. He thought that it might be phlogopite, but could not be certain.
Bismuth: Reported by Aho (1949). Thompson (1950) reported bismuth from the Barker workings on Haggart Creek, below its confluence with Dublin Gulch. Traill (1970) noted that “Bismuth occurs at Dublin Gulch, . . . , in the Mayo mining district as a minor constituent in a gold placer deposit (X-ray Laboratory, Geol. Surv. Can.).” No further details were given – perhaps this is from the material collected by Thompson in 1943?
Bismutite: Templeman-Kluit (1963) identified this by X-ray analysis, adding that extra lines in the pattern “. . . may be those of tetradymite.” See note below for tetradymite. Traill (1970) noted that bismutite was found at Dublin Gulch with bismuth, and that “It was identified by X-ray diffraction in the X-ray Laboratory of the Geol. Surv. Can.” He gave details of the six strongest lines of the pattern.
Cassiterite: This was originally confirmed by the Geological Survey of Canada (see Thompson, 1945, Traill 1970). Templeman-Kluit (1963) also confirmed the X-ray determination. The Pacific Museum of Earth has three specimens (#2101, #4059 and #6671) of placer cassiterite from Dublin Gulch.
Chlorite: Thompson (1945) described chlorite in “. . . angular fragments of . . . vein quartz embedded in chlorite, cassiterite and tourmaline.”
Ferberite: Reported by Aho (1949), and X-ray confirmed by Tempelman-Kluit (1963), who described two types and noted that “Both types give identical patterns and are apparently free from Mn.” The Pacific Museum of Earth has two specimens (#4528 and #6913) of placer ferberite from Dublin Gulch, both labelled as “pseudomorph.”
Ferritungstite?: Tempelman-Kluit (1963) listed ferritungstite as X-ray confirmed, but a hand-written note by Dr. R. M. Thompson said “Check”, and as this is not listed in Back (2018), this is an invalid species. It is not known what species he X-rayed.
Galena: Apparently not common; identified by Aho (1949) and Tempelman-Kluit (1963).
Galenobismutite: Reported by Thompson (1950), who remarked that “This rare mineral was found surrounding a small nugget of gold from the placer workings of Mr. F. Taylor.” The Pacific Museum of Earth at UBC has a specimen (#2022), presumably that described by Thompson, consisting of a very small grain of gold with galenobismutite in a glass tube – the label says “Gold Galenobismutite Qtz Dublin Gulch Yukon”.
Garnet: Reported by Aho (1949) and by Tempelman-Kluit (1963). The latter, noted that “The specific gravity of 5 grains averaged 4.26 indicating a composition near the almandine end of the garnet series.” Without further work, this specific identification must be regarded as tentative.
Gold: This being a gold placer operation, the mineral is common. Thompson (1945) reported that “Samples of gold collected from the Gulch were spectrographically analyzed, and tin was found to be a consistent minor constituent of the gold and strongly suggests that the tin and gold are genetically related.” Traill (1970) noted that “Placer gold in addition to lode gold, occurs at Dublin Gulch. A specimen from the area, now in the National Mineral Collection consists of quartz, scheelite, magnetite and gold.” The Pacific Museum of Earth at UBC has a collection of bright distorted elongate gold grains (specimen #3616) from Dublin Gulch.
Hematite: Reported by Aho (1949) and by Tempelman-Kluit (1963). The latter confirmed the identification by X-ray analysis, noting that some extra lines in the pattern might be from anatase. The Pacific Museum of Earth at UBC has a specimen (#1459) of some rounded pebbles with finely disseminated hematite.
Ilmenite: Reported by Aho (1949) and by Tempelman-Kluit (1963).
Jasper: Reported by Tempelman-Kluit (1963).
Molybdenite: Reported as fine flakes and X-ray confirmed by Tempelman-Kluit (1963).
Monazite: X-ray confirmed by Tempelman-Kluit (1963).
Pyrrhotite?: Tempelman-Kluit (1963) noted that “A single fragment of quartz with a small grain of a pyrrhotite like mineral was found in the magnetic +28 fraction.” It should be regarded as tentative for the locality.
Rutile: Reported by Tempelman-Kluit (1963).
Scheelite: This was reported in the early days of the placer operations at Dublin Gulch (Keele, 1905). It was regarded as a major nuisance; because of its high specific gravity and abundance, it tended to clog the sluice box riffles and make gold recovery difficult. It was the most abundant mineral in the jig concentrate studied. Tempelman-Kluit (1963) reported that the mineral fluoresced white under ultraviolet light, and that the average of five specific gravity determinations was 6.08, indicating “. . . little or no molybdenum in substitution for W.” The Pacific Museum of Earth at UBC has two specimens (#3262 and #6914), the latter with ferberite.
Scorodite: Tempelman-Kluit (1963) reported that “The pebbles are often coated with yellowish green scorodite.” However, see the comment above for beudantite; Tempelman-Kluit did not X-ray this coating.
Spinel: Tempelman-Kluit (1963) reported that “This mineral occurs as translucent green black octahedra and fragments of ocatahedra in the .2 - .4 mm size range. An X-ray powder photograph of very similar looking spinel found in place in the vicinity of Dublin Gulch gave a hercynite pattern . . . with a cell edge 8.16Å.”
Tetradymite: Reported by Aho (1949) and X-ray confirmed by Thompson (1949). Traill (1970), referring to Thompson’s paper, noted that “A small pebble of tetradymite containing an embedded subhedral crystal of gold has been found in placer workings at Dublin Gulch, Mayo District . . . .” The Pacific Museum of Earth at UBC has a specimen (#162), likely that described by Traill, consisting of a very small grain of gold with tetradymite, in a glass tube.
Tremolite: Tempelman-Kluit (1963) found “. . . small clear light green prisms with amphibole cleavage.”, and confirmed the identification with an X-ray powder analysis.
Tourmaline: Reported by Thompson (1945); see note above for chlorite.
Wolframite?: In Tempelman-Kluit (1963) there is a handwritten note by Dr. R. M. Thompson – “I wonder if we have both ferberite and wolframite?” Further to this, The Pacific Museum of Earth at UBC has a group of specimens (#3825) consisting of 2 to 3 cm rounded pebbles of a black mineral with scheelite, which is labelled “wolframite” but has no further data. This should be regarded as tentative at this time.
Wüstite: Tempelman-Kluit (1963) found five spherical micrometeorites in the magnetic fraction. “An X-ray photograph of one indicated the presence of magnetite and wustite +.”
Zinc: Tempelman-Kluit (1963) found a single 0.5 mm long grain, which he X-rayed and found to be native zinc, with some additional lines he could not identify. Note that Boyle (1961) described native zinc in the oxidized zones of some of the mines in the Keno Hill area.
Zircon: Reported by Aho (1949) and by Tempelman-Kluit (1963).

References

Other Databases

Canada Yukon Survey:	13910

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