Ref.: Rocks & Min.:6:77. A silver mine located on the Skeena River. Produced approx. 325,000 oz. silver/yr.

The former Duthie Mine is located on the south-west slope of Hudson Bay (note spelling) Mountain, about 13 kilometres west of Smithers, British Columbia. The mine property covered several vein occurrences; other properties listed on MINFILE include: DOME (093L 089); CORONADO (093L 090); MAMIE (093L 091); and HUMMING BIRD (093L 095) – note the spelling, in many reports this is given as HUMMINGBIRD.
The following quote is from B.C. Government site “Minfile”- Minfile No. 082KNE 013, current to 1991:
“The Duthie mine country rock consists of Lower-Middle Jurassic Hazelton Group volcanics comprised mainly of spherulitic flow-banded rhyolite and massive lapilli tuff which is cut by numerous diabasic and dioritic dikes. The flow-banded rhyolite outcrops along the southern part of Hudson Bay Mountain and is overlain to the north, east and west by massive lapilli tuff. The contact dips 20 degrees north at about 1220 metres in elevation on the Henderson vein. In the vicinity of the veins the host rock is highly altered and bleached.
A Middle-Late Cretaceous Bulkley Intrusions stock intrudes the core of Hudson Bay Mountain and is comprised of porphyritic granodiorite and quartz monzonite with associated quartz veining.
The mineral deposits of the Duthie mine occupy four main fault zones, originally known as the Ashman, Henderson, Fault Plane and Dome. The mineralized fault zones or "vein-lodes" strike northeast and dip between 50 degrees southeast to 70 degrees northwest. They range from a few centimetres to 2.4 metres in width and from 213 to in excess of 1067 metres in length. The vein lodes are sliced, sheared and brecciated and host sulphide veins or infillings with vein quartz and carbonate gangue. The main ore minerals are galena, sphalerite, tetrahedrite, pyrargyrite, pyrite, arsenopyrite, gold, chalcopyrite, silver and freibergite. Ore from the Henderson-Ashman lode also contains pyrrhotite and marcasite. All the ore contains gold and rare visible gold is associated with the arsenopyrite. The ore is associated with minor quartz and carbonate gangue and is crosscut by younger chalcedony veins up to 5 centimetres in width.
There is a progressive change in the mineralization in a northeast direction along the Henderson-Ashman vein lode as the deposit approaches the granodioritic stock which forms the core of the mountain. The galena-sphalerite-tetrahedrite ore changes to arsenopyrite-sphalerite ore that contains more gold and zinc but less galena and silver.
The Henderson vein lode is marked by intense faulting and more brecciation than the other veins and has proved to be the most productive. It outcrops between 1082 to 1280 metres elevation for about 610 metres and then joins the Ashman vein lode. The combined veins have been traced to the northeast for 460 metres at 1360 metres elevation. The Henderson vein strikes 065 degrees and dips between 50 degrees southeast to 80 degrees northwest. The Ashman vein is traceable for 520 metres southwest of its junction with the Henderson.
At 1090 metres elevation, the Henderson vein joins the Fault Plane vein lode and the two veins plunge at a low angle southwest. The Henderson vein has a near vertical dip, whereas the Fault Plane striking nearly parallel, dips 55 to 60 degrees southeast.
The fourth vein, the Dome (093L 089), lies 400 metres southeast of the Henderson and strikes 065 degrees and dips 75 to 85 degrees northwest. The Dome vein is well-defined for 215 metres.”
Comments by Giles Peatfield regarding some of the minerals reported:
Albite: Kindle (1940) described a quartz-albite dyke cutting the Henderson vein.
Anglesite: Clarke (un-dated) reported anglesite as a possible alteration of galena, along cleavage planes. I regard it as probable.
Bornite: This was reported only by Roberts (1948), as inclusions with chalcopyrite in sphalerite.
Covellite: This was reported only by Jones (1926) from the Henderson Mine. He noted that “In one specimen a minor amount of covellite cuts both galena and chalcopyrite.”
Dyscrasite: This was reported as possible by West (1952), from the Humming Bird vein. He found a single 70 micron diameter grain, contained within a grain of “silver-rich electrum”, which was in turn contained within galena. He tentatively identified this as dyscrasite, based on etch reactions and what he described as a “characteristic grating structure.” In the acknowledgement section of his report, West thanked Dr. R. M. Thompson “. . . for his suggestions leading to the identification of the Dyscrasite.”
Electrum: This was reported by West (1952), from the Humming Bird Vein, as grains within galena, averaging 30 – 40 microns and never greater than 90 microns. It had variable colour, with most grains pale yellow.
Freibergite: For this, see comment below for tetrahedrite.
Gold: This was reported as “possible” by Little (1936?) from the Mamie Vein, and by West (1952) from the Humming Bird Vein. Little examined polished sections under 540 diameters, and in one found “three minute particles” in late quartz in contact with sphalerite. Dr. Harry Warren concurred with Little in this identification. West was not certain about gold, basing his tentative identification on colour.
Greenockite: West (1952) described a coating on sphalerite grains from the Humming Bird Vein that he thought might be greenockite, but this was not backed up by any hard data and I would regard it as tentative at best.
Marcasite: West (1952) described marcasite, from the Humming Bird Vein, that he interpreted as an alteration product of early pyrrhotite. Antoniolli (1952) described marcasite from the Mamie Mine, which he described as follows: “Marcasite is found along fractures filled with dark carbonate. It has replaced the pyrrhotite along the basal planes, and occurs in two varieties: one is white [and] remarkably anisotropic, in lath-like crystals, and its total amount may be about 5% of the amount of pyrrhotite; it contains myriads of sphalerite particles . . . and may assay up to 25% zinc; the other variety, present in very minor amounts, is light brown, slightly anisotropic and shows colloform banding . . .; it is probably contemporaneous with the first and does not contain any sphalerite.” Antoniolli gave extensive information regarding his process of separating different mineral phases for assay – interested readers are referred to his report (Minfile PF600303). It would seem to be very likely that marcasite occurs in this material, but that there may be a second unidentified mineral.
Native silver: This has been reported by several workers.
Pyrargyrite: This has been reported by several workers, in some cases as “ruby silver”. None of these authors report X-ray confirmation, but the Pacific Museum of Earth has a specimen (catalog number 690 – M3211 A16) from the Duthie Mine which is listed as pyrargyrite.
Pyrolusite: Leach (1909) reported, from the Humming Bird Claim, “. . . a black, earthy material on the surface which in the laboratory was proved to consist largely of pyrolusite.”
Rhodochrosite: Kindle (1940, p. 92) reported rhodochrosite with no qualification. Clarke (un-dated) was not so certain, stating that “A microchemical test showed that the carbonate contained manganese. It is either manganese bearing siderite or rhodochrosite.” I would agree, based on the presence of pyrolusite reported by Leach (1909), that there is a manganese bearing carbonate, whether or not it is actually rhodochrosite is uncertain.
Tetrahedrite: Galloway (1923) reported on the analysis of two samples of “grey copper” (tetrahedrite) from the Henderson vein, “. . . as nearly pure as possible to obtain . . . .” The results averaged: 21.25% S, 25.25% Sb; 18.5% Cu; 4.5% Fe; 3.25% Zn; and 26.05% Ag. Based on this, Galloway reported that the mineral “. . . is so rich in silver as to belong to the classification of ‘freibergite’.” Some uncertainty arises from the fact that Clarke (un-dated) described, probably from the Henderson vein, “An intergrowth [that] is included under this name (tetrahedrite) and most probably consists of tetrahedrite and freibergite. They both displayed the same etch tests as tetrahedrite.” Furthermore, he stated that “One of the minerals of the intergrowth contains usually small inclusions of chalcopyrite and galena, whereas the other mineral is barren.” West (1952) reported, from the Humming Bird vein, a mineral that he thought might have been freibergite, but gave no firm data to substantiate this. On balance, one can say that there is tetrahedrite, and that at least some of it is probably freibergite.
Unknown: Clarke (un-dated) described an “unknown” mineral, occurring as fine needles contained in galena, and following definite crystallographic directions. However, he provided no further data, so it is not possible to speculate on what this might be.

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Mineral List

21 valid minerals.