Blue Moon Metals Inc. (BMM), holds the mineral rights to the unpatented mining claims and patented (private) lands associated with the Blue Moon deposit (Blue Moon Property) through its wholly owned subsidiary, Keystone Mines Inc.
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Summary:
The Gopher Ridge Formation in the area of the Blue Moon deposit consists of a basal sequence of basalt and andesite overlain by a rhyolite. The rhyolite strata are up to 300 m thick and host the Blue Moon deposit(s). The sulphide-sulphate mineralized lenses are hosted in the lower part of the felsic sequence. The felsic volcanic rocks are succeeded to the east by volcaniclastic rocks and ultimately by deep-water argillaceous, sedimentary rocks (Meade, 1996).
Strata at Blue Moon strike approximately 20° west of north, dip near vertically, face to the east and are tightly folded. Minor fold features suggest a steep, north plunge of the regional structure. All lithologies have undergone low grade metamorphism characteristic of the lower greenschist facies.
The rhyolite strata have been subdivided on the basis of phenocryst mineralogy into three distinct units: aphyric rhyolite, feldspar porphyry rhyolite and quartz-feldspar porphyry rhyolite. The thinning of the aphyric rhyolite proximal to the domes defines favorable environments for deposition of massive sulphide mineralization. Further up the stratigraphic sequence, massive feldspar porphyry rhyolite appears to define sill or dyke features that locally truncate sulphide mineralization.
Lateral to the sulphide mineralization are chemical sedimentary rocks containing hematite, magnetite, barite, silica and manganese minerals, which help define mineralized horizons. Sulphide-barite mineralization on the edges of massive sulphide mineralization grades laterally into hematite-jasper iron formation, which, in turn, grades into manganese-bearing siliceous tuffaceous rock.
The Blue Moon deposit is a Kuroko-type, polymetallic, volcanogenic, massive sulphide deposit, or VMS deposit. The sulphide-sulphate deposit is hosted in rhyolite. Anomalous metalliferous mineralization includes pyrite, sphalerite, chalcopyrite, galena, and minor tetrahedrite and bornite. The associated sulphate minerals are barite, gypsum and purple anhydrite. To date, four lenses of mineralization have been identified within at least two, possibly three, horizons. The lenses are enveloped by sericite-silicapyrite alteration. Gold and silver grades are significant in the lower horizon lenses but are, on average, three times greater in the upper horizon lenses.
Mineralization
The Blue Moon deposit is a Kuroko-type volcanogenic massive sulphide deposit. The deposit is shown to have some similarities with the Lynx and Myra deposits at Myra Falls, Vancouver Island. Stacked sulphide-sulphate lenses occur in two or more horizons within a 50 ft to 180 ft stratigraphic interval. Four distinct lenses of massive sulphide mineralization have been identified; the West, Main, East and American Eagle zones. The American Eagle Zone appears to occur in the same stratigraphic position as the West Zone.
The West Zone occupies the lowest stratigraphic position and occurs near the base of the aphyric rhyolite sequence. The Main Zone lies stratigraphically above the West Zone and occurs with the first appearance of quartz and feldspar porphyry rhyolite. The East Zone lies stratigraphically above the Main Zone, although several authors have included it as part of the Main Zone. It is hosted entirely within feldspar porphyry rhyolite.
Massive sulphide mineralization consists of pyrite, sphalerite, chalcopyrite, galena, and minor tetrahedrite and bornite. Massive and semi-massive sulphides may be accompanied by purple anhydrite, gypsum or barite. Textures include massive, banded and clastic mineralization.
Metal zoning in base or precious metal is poorly understood although there is a strong tendency for narrower mineralized zones to be relatively richer in gold and silver and to have barite gangue.
The potential mineral horizons are enveloped by sericite-silica-pyrite alteration that extends laterally in the rhyolite stratigraphy at least 3,000 ft, as far as known mineralization is recognized, and more than 490 ft into the footwall andesite. A stockwork sulphide feeder zone is not clearly identified within the footwall alteration zone. This discordant sericite altered zone is linked to a lower strata-bound sericite altered zone in the footwall andesite which extends at least 0.7 miles to the south from the deposit and may be an important exploration tool to identify other mineralized centres.
The lower mineralized horizon (West and American Eagle zones) generally contains more pyrite, chalcopyrite, sphalerite, anhydrite and gypsum than the upper mineralized horizon (Main and East zones) which is comparatively enriched in galena, tetrahedrite and barite. The South Zone has not been studied. Gold and silver grades can be significant in the lower horizon lenses but are on average three times greater in the upper horizon lenses.