Centre Star (Wesko) Mine, Ymir, Nelson Mining Division, British Columbia, Canadai

Regional Level Types
Centre Star (Wesko) Mine	Mine
Ymir	Village
Nelson Mining Division	Division
British Columbia	Province
Canada	Country

The Centre Star (Wesko) Mine is located south of Oscar Creek, about 2 kilometres east-southeast of the unincorporated settlement of Ymir, or 24 kilometres south-southeast of Nelson, British Columbia, in the Nelson Mining Division. Note that the British Columbia “Minfile” site lists the name as “Center Star” – this is incorrect; the claim was “Crown Granted” (patented for USA readers) on 23 March 1905, Grantee J. S. C. Fraser et al., as the “Centre Star” – see Annual Report of the British Columbia Minister of Mines for 1905, p. J251. “Minfile” also states that the location of the mine is “. . . on the west slope of Jubilee Mountain, about 1.6 kilometres northeast of Ymir.” This is not correct – see the location given above.
There is a description of the property, including regional geology, on the British Columbia “Minfile” site, current to 1991. A portion relative to geology is quoted below:
“The area is underlain by Jurassic Ymir Group sediments. The sheared and altered argillites and quartzites are intruded by the Nelson batholith comprising granite and granodiorite of the Middle to Late Jurassic Nelson Intrusions. Prominent shear zones, 5 to 10 metres wide, trending 30 to 55 degrees east with vertical or steep southeast dips, crosscut the host rocks. On the property, two such parallel shear zones occur about 122 metres apart.
Mineralization occurs in a broad contact zone consisting of sheared and altered argillites and quartzite intruded by granite. Ore shoots occur in veins, up to 8 metres wide, along fault fissures striking 280 to 300 degrees and dipping steeply northwest.
The deposit comprises a 152 metre long mineralized vein, dipping steeply northwest, occurs within a 1 to 2-metre wide fracture. The vein strikes 60 to 80 degrees east, diagonally between the two major northeast trending shear zones, and is terminated by shears. Ore shoots with an easterly pitch are developed at the intersection of the vein with northwest trending fractures. The fractures also host sulphides but they contain negligible to zero gold. Tongues of intrusive granite are close to the ore shoots.
Gangue consists of quartz and brecciated, siliceous country rock fragments, with pyrite, galena, sphalerite and pyrrhotite. Pyrrhotite is less common in the upper levels. Near surface, the vein is oxidized with limonite, manganite and pyromorphite stained by cerussite.”
Giles Peatfield comments:
The Centre Star (Wesko) Mine is a small past producing silver, gold, lead and zinc mine, with relatively simple geology and mineralogy. I have chosen to present it because it is a locality for pyromorphite, which is a relatively uncommon mineral in British Columbia (see note below in the mineral section).
The Centre Star Mine was mined in a modest way, discontinuously between 1936 and 1950, producing silver (the principal product) and gold, as well as substantial amounts of lead and zinc. Of this, most of the tonnage was milled locally in the period 1936-1938. In successive years, small operators mined a few tonnes yearly, which were shipped to a smelter, probably the CM&S facility at Trail, British Columbia. Official figures on the British Columbia “Minfile” site show that the total ore mined amounted to 51,458 tonnes (56,722 tons), of which 50,595 tonnes (55,771 tons) was milled locally. The total yield from the mine is reported as 2,955,219 grams (95,012 troy ounces) silver; 386,145 grams (12,415 troy ounces) gold; 966,401 kilograms (2,130,550 pounds) lead; and 475,628 kilograms (1,048,580 pounds) zinc.
Giles Peatfield comments on the minerals reported:
Given the number of different workers and the time frame involved, I have chosen to comment on all the minerals so far reported at this property.
Arsenopyrite: Timm (1937) reported that arsenopyrite was “rare”; in polished sections “A small amount of arsenopyrite occurs as crystals in pyrite, . . . .”
Cerussite: Reported by Cockfield (1936), and by McAllister (1951), who it seems was simply listing the minerals reported by Cockfield.
Chalcopyrite: Timm (1937) reported that in polished sections “A very small amount of chalcopyrite is associated with the sphalerite, although there is a notable absence of the usual fine dots of chalcopyrite in this mineral [sphalerite].”
Chlorite group?: Timm (1937) reported that “Stringers of green chloritic (?) material are present.”, but gave no specific data.
Galena: Reported by all workers.
Gold: Timm (1937) reported that, in one of the shipments of ore provided, “Native gold is present in the quartz as small irregular grains which tend to occur along fractures which often contain ‘limonite’.”
Limonite: Reported by all workers.
Manganite: Reported by Cockfield (1936), who commented that “On the surface the veins are thoroughly oxidized and the vein matter consists of honeycombed masses of limonite, quartz, and manganite, together with some pyromorphite.” See comment below.
Pyrite: Common, reported by all workers.
Pyromorphite: This is mineral of principal interest for this review. O’Grady (1935) wrote that “Pyromorphite was identified in one showing, assays showing up to 3 per cent. lead.” Cockfield (1936) added a footnote, to say that “The determination [of pyromorphite] was made by Mr. E. Poitevin, Mineralogical Division, Geological Survey.” This is one of a few localities reported to date for this mineral in British Columbia. The Pacific Museum of Earth at the University of British Columbia has a specimen (No. 3464) donated by H. V. Warren, described as from the Wesco [sic - Wesko] Outcrop.
Pyrrhotite: Reported by Cockfield (1936) and seen in polished section by Timm (1937), who said that it was common, locally massive, admixed with galena.
Quartz: This is the main vein gangue mineral.
Sphalerite: Reported by all workers; Cockfield (1936) called it “zinc blende”. As noted above, Timm (1937) found it, in polished section, to be apparently largely free of the so-called exsolution “chalcopyrite disease” [my comment].
Tetrahedrite group: Timm (1937) described “tetrahedrite-tennantite” but gave no further details. He further commented that “It is probable that the silver [range 1.88 to 5.11 oz/ton in the three shipments received] occurs chiefly in the tetrahedrite-tennantite and galena, and would thus concentrate with the galena.”
Giles Peatfield comments on the rock types reported:
Most of these rock names were reported by McAllister (1951), except for granodiorite, reported by Cockfield (1936), and schist, reported by O’Grady (1935). As far as can be ascertained, these are all field names.

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Link to British Columbia Minfile:	082FSW066

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