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Moonshine Mine, Lardeau District, British Columbia; Mineralogy

Last Updated: 26th Apr 2018

By Richard Gunter

Moonshine Mine, Lardeau Area, British Columbia; Mineralogy

Richard Gunter
5493 Cedarcreek Drive
Chilliwack, British Columbia
pamrichg@shaw.ca



Abstract:

The Moonshine Mine is a small, intermittently mined lead-silver deposit in the Kootenay Area of eastern British Columbia. The deposit is unusual because it has a well-defined secondary weathered zone with the oxidation minerals normal to these deposit types: smithsonite, aurichalcite, cerussite, anglesite, hydrozincite and minium as well as the less common woodruffite and gunningite.

Supergene alteration zones of base-metal deposits are locally present throughout the Canadian Cordillera. They have been examined by government geologists and companies interested in the lead-zinc and porphyry copper deposits that these supergene zones develop from. They are often not as extensive or as colourful as the more heavily weathered copper-lead-zinc deposits further south in Montana and Idaho.


Table of Contents:

Abstract:

Figures and Images:

Introduction:

Geology:

Mineralogy:

Sulphides:

Galena

Oxides:

Minium

Woodruffite

Goethite

Carbonates:

Cerussite

Aurichalcite

Hydrozincite

Gunningite

Sulphates:

Anglesite

Silicates:

Quartz

Conclusions:

References:


Figures and Images:

Figure:

Figure 1: Geological Map of the Moonshine Mine Area; Fyles (1964)

Images:

Image 1: Minium and Galena; Moonshine Mine
Image 2: Goethite; Moonshine Mine
Image 3: Woodruffite; Moonshine Mine
Image 4: Woodruffite-Smithsonite; Moonshine Mine; from Sabina (1978)
Image 5: Aurichalcite; Moonshine Mine
Image 6: Pyromorphite; Society Girl Mine, British Columbia
Image 7: Botryoidal Hemimorphite; Sa Dena Hess Mine, Yukon Territory
Image 8: Azurite and Malachite; Highland Valley Mine, British Columbis
Image 9: Cerussite and Massicot; Bunker Hill Mine, Idaho
Image 10: Pyromorphite; Bunker Hill Mine, Idaho


Introduction:

The Moonshine Mine (B.C. Minfile designation), near the small village of Lardeau in south central British Columbia is a small lead-zinc-silver producer that was mined intermittently from 1951 to 1968 and produced a total of 573 tonnes of lead-silver ore. The mining was completed by the Willett Mining Company and the mine is sometimes known as the Willett Mine in the literature (Ingelson (1984) and the Moonshine Mine in the Federal and Provincial Government databases.

This is one of a number of lead-zinc-silver-gold deposits in the Badshot Limestone Formation in the Kootenay region of British Columbia and would not be notable except that the mine had one of the few with a well-developed weathered zone. The zone contained oxides and carbonates of lead, zinc and copper in a porous iron-oxide gossan. The mine was accessible to collectors as it was abandoned after 1968. The small dumps and adit could be reached by car in the early 1980’s.



Geology:

A Brief outline of the deposit in the British Columbia Minfile database says: The Moonshine prospect is located on Crown grant Lot 1881, one kilometre south of the Davis Creek bridge on Highway 31, south of Lardeau, in the Slocan Mining Division. Regionally, the area lies within the Kootenay Arc near the margins of the Ancestral North American Terrane. The Kootenay Arc is a curving belt of highly deformed metasedimentary and metavolcanic rocks which includes the Upper Proterozoic Horsethief Creek Group, the Eocambrian Hamill Group, the Lower Cambrian Badshot Formation, and the lower Paleozoic Lardeau Group. The volcano-sedimentary sequence is intruded by numerous Ordovician, Devonian and Mississippian granitoid plutons. The rocks have undergone regional metamorphism to middle or upper greenschist facies (Paper 1993-1).


The mineralization is hosted by grey and white crystalline limestone of the Lower Cambrian Badshot Formation which is overlain by brown micaceous quartzite of the Marsh Adams Formation of the Hamill Group and phyllite of the Index Formation of the Lardeau Group. The rocks strike northwest and dip 15 to 20 degrees southwest. The limestone forms steep bluffs above and south of the workings. Massive galena, sphalerite and minor chalcopyrite occur with minor quartz in a narrow discontinuous fracture that strike northeast and dip 65 degrees northwest. The sulphides are present both as fillings of the fracture and as replacement of the limestone, near the base of the unit. Quartz is mainly along the footwall of the fracture. The mineralized fracture ranges in thickness from a few centimetres up to almost 2 metres. Lenses of coarse massive sulphides, up to 1.5 metres long and 30 centimetres, wide occur along the fracture and constitute the best ore. Limited mining between 1951 and 1968 produced 188,868 grams of silver, 98,366 kilograms of zinc, 86,748 kilograms of lead, 437 kilograms of copper and 31 grams of gold from 573 tonnes milled.

The Mineralogical Record has also completed a brief article in the Willett Mine (Ingelson (1984)). Alan Ingelson collected the samples and wrote-up the article based on the results from Sabina (1978). The Mineralogical Record article was largely a property description and the Sabina article was a mineralogical description. Ingelson indicates that the Willett Mine produced specimens of: woodruffite, gunningite, smithsonite, aurichalcite, kaolinite, hydrozincite (pale blue fluorescence in SW UV), galena, sphalerite and goethite from “heavily oxidized limonite zones within the stope”.

Sabina (1978) says: These minerals are associated with smithsonite which occurs in the silver-lead zinc deposit (Moonshine claims) formerly (1954-1957) worked by Willett Mines Limited near Lardeau, British Columbia (82K/2). The ore mineralization consists of galena and sphalerite with minor chalcopyrite and quartz in fracture zones in Lower Cambrian crystalline limestone (Fyles, 1964). The workings consist of adits, a shaft and trenches.


Figure 1: Detailed Geological Map of the Moonshine Mine; scale 1:63360; from Fyles (1964).
Geological Map of the Moonshine Mine from Fyles (1964)

Moonshine Mine, Lardeau, Revelstoke Mining Division, British Columbia, Canada


The geology map illustrates the north-south trending strata in the area of the Moonshine Mine.The Moonshine Mine is noted on the western edge of the lake, just south of the village of Lardeau.


Mineralogy:

Sulphides:

Galena (PbS):

Coarse-grained cleavages of brightly lustered, metallic galena with a 2 mm. thick layer of fine grained cerussite-anglesite occur coated with bright red minium within the dull red goethite-bearing gossan. The coarse galena is mixed with colourless quartz and some dark-brown coloured sphalerite.


Oxides:

Minium (Pb2PbO4):

Deep red, earthy minium coats the cerussite-anglesite coating on the galena-quartz fragments. The minium does not crystallize directly from the galena. The coating Image 1 Minium on Cerussite/Anglesite

is a distinctly redder colour than the goethite Image 2 Goethite with Aurichalcite.

The minium- anglesite- cerussite oxidation rinds around the galena grains were not noted in either Ingelson (1984) or Sabina (1978).

Woodruffite (Zn,Mn)Mn3O7.2-4 H2O):

Black semi-metallic botryoids of woodruffite Image 3 Woodruffite on Goethite

occur deposited on the goethite of the gossan. Sabina (1978) in her mineralogical description says: The woodruffite is black with a lustre that varies from sooty to velvety, greasy and submetallic. It occurs in smithsonite occupying spaces between the fibrous cap and the crystalline aggregates, and admixed with crystalline massive smithsonite.

Beneath the fibrous cap, which is I to 2 mm thick, woodruffite occurs as paper-thin, concentric layers forming spheres and hemispheres conforming to the botryoidal cap of smithsonite. The layers are smooth, finely botryoidal or crinkly and friable, and commonly have open spaces between the layers. Woodruffite also occurs as randomly oriented thin plates and scales, and as finely granular aggregates admixed with and occupying pockets in crystalline aggregates of smithsonite.


Goethite (FeOOH):

Goethite is a brown pulverant phase that makes up the majority of the gossan. It is occasionally vugs the smithsonite and aurichalcite lining cavities.


Carbonates:

Smithsonite (ZnCO3):

Smithsonite occurs as white botryoidal aggregates often associated with woodruffite. Sabina (1978) says: The specimens examined consist of masses of crystalline smithsonite capped by radiating fibrous smithsonite producing botryoidal surfaces. The mineral is grey with a vitreous lustre. Ingelson (1984) says: Most of the smithsonite is greyish blue, however dark green, white an (sic) black specimens were also collected.

Image 4: Woodruffite in botryoidal smithsonite, Willett Mines Limited property, Lardeau, British Columbia. X 10 (GSC 203094-R).

Cerussite (PbCO3):

Occurs as a fine-grained tan-coloured coating on altering galena and coated by minium embedded in the gossan.

Aurichalcite ((Zn,Cu)5(CO3)2(OH)6:

Sabina (1978) says: Aurichalcite, as light blue flaky aggregates, is associated with the fibrous smithsonite. Some of the Aurichalcite, Image 5 is much better crystallized and illustrates platy green –blue crystals coating cavities in goethite associated with botryoidal smithsonite and black, botryoidal woodruffite.

Hydrozincite Zn5(CO3)2(OH)6:

White, powdery, blue fluorescent phase that Sabina (1978) says: hydrozincite as white, compact, powdery, and finely botryoidal crusts.


Gunningite (ZnSO4.H2O):

White, powdery, non-fluorescent phase that Sabina (1978) says: Gunningite occurs as white, earthy, crumbly aggregates.

Sulphates:

Anglesite (PbSO4):

Occurs as a fine-grained tan-coloured coating on altering galena and coated by minium embedded in the gossan.

Silicates:

Quartz (SiO2):

Quartz is a colourless, coarse grained, gangue mineral that occurs with the lead-zinc veins. It is intergrown with galena in the goethite gossan.


Conclusions:

The Moonshine (Willett) Mine is a small, intermittently mined, lead-zinc-silver deposit similar to many in the Kootenay Region of British Columbia and further south in similar strata in Idaho and Montana. It is noted mainly as one of the few lead-zinc-silver deposits in Canada to have a significant weathered horizon with secondary copper and zinc minerals such as aurichalcite.
Ingelson (1984) indicates that the preservation of the secondary minerals may be due to the location of the deposit at the base of significant limestone cliffs.

An example of a similar vein in the same geographic area was mined by the Society Girl Mine. Image 6: Pyromorphite and Cerussite, Society Girl Mine, British Columbia The mine produced pyromorphite in significant quantity to be internationally recognized. Ingelson (1984)says: This mineral occurrence has produced Canada’s finest pyromorphite crystals. Excellent quality, bright green, barrel-shaped crystals have been collected from this property form many years since the original mining efforts for high grade lead-silver ore in the early 1900’s.

The British Columbia Minfile says: The main vein is from 2 to 5 centimetres wide, strikes 300 degrees and dips 60 degrees south. The vein tends to be narrow within thin-bedded, argillaceous quartzites and widens in thicker, more massive quartzites. The vein is highly oxidized to a depth of approximately 10 to 15 metres from the surface and the oxidized ore is composed of massive and well-crystallized cerussite and pyromorphite embedded in a matrix of clays and limonite. Minor traces of malachite and azurite were recorded. Below the oxidized zone the vein consists of galena and sphalerite with little or no quartz gangue. They also say that the oxidation zone in the Society Girl Mine is rare in British Columbia.

The discovery of several zinc-rich non-sulphide zones within stratabound lead-zinc deposits in British Columbia and the Yukon; for example botryoidal hemimorphite and smithsonite at Sa Dena Hess, Yukon Territory Image 7: Botryoidal Hemimorphite Sa Dena Hess Mine, Yukon

and secondary minerals associated with porphyry copper deposits Image 8: Azurite and Malachite from Highland Valley, British Columbia

These localities illustrate that the preservation of secondary minerals in the Cordilleran mineral deposits is widespread in small amounts.

The varying geology and geography of these mines illustrates that the presence of secondary minerals is not tied to a specific geographical circumstance. The rarity of secondary alteration was the result of poor recognition of the often less-than-colourful non-oxide zinc deposits. That has been remedied by the British Columbia Geological Survey’s programs on non-sulphide zinc (Paradis and Simandl (2010)).

Small to medium sized lead-zinc-silver occur on the Canadian side of the border but much larger and economically more important deposits occur at Metalline, Washington and Coeur d’Alene, Idaho, just south of the Canadian Border. The latter containing a significant oxidation zone with cerussite and pyromorphite Image 9: Cerussite and Massicot Bunker Hill Mine, Idaho Image 10: Pyromorphite, Bunker Hill Mine, Idaho.

The Coeur d’Alene oxidation zone is not unlike the Society Girl oxidation but the Bunker Hill Mine is much larger in volume than the Society Girl Mine, as is the oxidation zone.


References:

British Columbia Minfile Database: Moonshine Mine.

Fyles J.T. (1964) Geology of the Duncan Lake Area, Lardeau District, British Columbia; Geological Survey of Canada, Bulletin B049

Ingelson A. (1984) Mineral Occurrences in Western Canada; Mineralogical Record, v. 15 no. 2, pp. 89-94

Paradis S. and Simandl G.J. (2010) Carbonate-hosted, Nonsulphide Zn-Pb (supergene); Mineral Deposit Profile B09: British Columbia Geological Fieldwork 2010; Paper 2011-1, p. 189-193

Sabina A.P. (1978) New Mineral Occurrences in Canada Current Research Pt. A; GSC Paper 78-1A, pp. 253-258




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