Summary:
The Property includes ten mineralized zones: South, Lear, Alpine, Brookmere, Line 6, Mik, Tower, Forget Me Not (“FMN”), Franz, and Romeo Zones. Mineralization occurs in these Zones as gold-silver bearing quartz vein zones, largely hosted in a rhyolite dome, with the primary vein system extending for more then 4 km.
Deposit Type
Mineralization at the Shovelnose Gold Property - South Zone is typical of low-sulphidation epithermal systems in subaerial volcanic rocks.
Mineralization
Mineralization in the Vein Zones of the South Zone is dominated by ginguro, a cryptocrystalline, unsorted, amalgamated sulphide dust that precipitates as black, mm-scale bands along crustiform and colloform bands in vein zones (Izawa et al., 1990). Ginguro typically occurs as black bands, and locally may be discreet amalgamations of crystals. Sulphides present are chalcopyrite, electrum, naumannite, sphalerite, galena, pyrite and marcasite, with minor amounts of acanthite, aguilarite, tetrahedrite, greenockite (or hawleyite), Au-Ag selenide, hessite, pyrargite and miargyrite. Pyrite ± marcasite occur in association with veining and are generally observed peripheral to main vein zones and limited in extent. Visible massive or crystalline sulphides are very rare at the South Zone. Gold grades in ginguro-rich zones at the South Zone commonly exceed 30 g/t; for example, drill hole SN19-01 intersected 39.3 g/t Au over 12.66 m.
Mineralization textures observed at the South Zone are typical of epithermal vein systems with crustiform-colloform chalcedony and quartz textures. Crustiform components are the successive bands oriented parallel to vein walls, defined and distinguished by contrasting mineralogy, texture, and (or) colour. This banding is due to fluctuating contents of metals in solution and fluctuating fluid conditions during precipitation, caused by periodic boiling. The colloform components are fine rhythmic bands with a lobed, reniform (kidney-shaped) surface, and commonly an internally radiating form. Strong surface tension of the silica gel is responsible for the lobed, reniform external surface that is characteristic of colloform veins. Cockade textures are also observed locally and the terminology is restricted to crustiform bands that surround isolated rock (breccia) fragments. The comb texture is manifest by open-space growth and unidirectional growth of individual crystals nucleated on vein wall(s), giving rise to syntaxial or monotaxial veins. Moss texture is a recrystallization texture, whereby an original spheroidal gel texture recrystallized to chalcedony or quartz, and is indicative of very high degrees of silica supersaturation.
The electrum is intergrown with pyrite, chalcopyrite, sphalerite, galena and a variety of sulphosalts in trace amounts. The silver selenide naumannite (Ag2Se) is the most common sulphosalt observed with electrum. Aguilarite (Ag4SeS) was also observed. Native silver was observed enclosing electrum. These minerals all occur as complex composite grains generally.
Galena can contain a small amount of silver, or possibly includes a silver phase too fine-grained to observe. Enargite (Cu3AsS4) is the main sulphosalt phase. Eckerite (Ag2CuAsS3) and a silver telluride, possibly hessite (Ag2Te), were also observed.
In addition to the precious metal mineral phases, fluorapatite was observed to be intimately intergrown with sulphides, specifically pyrite in several samples. Selenium, mostly the arsenic end-member with minor antimony substitution in a few analyses, occurs in naummanite and aguilarite with electrum throughout the system. Vein carbonate is ferroan dolomite, with very minor Mn content. Clay and sericite occur as < 10 um size masses of scaly flakes interstitial to quartz in cloudy bands.