Artemis Gold holds a 100% interest in the Project through BW Gold Ltd., its wholly owned subsidiary and the operating entity for the Blackwater Gold Mine.
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Summary:
The Blackwater deposit is an example of a volcanic-hosted, epithermal-style gold-silver deposit.
Pervasive stockwork-veined and disseminated sulphide mineralization at Blackwater is hosted within felsic to intermediate volcanic rocks that have undergone extensive silicification and hydrofracturing.
The geological setting, style of gold-silver mineralization, and associated alteration assemblage for the Blackwater deposit share the characteristics of both low and intermediate sulphidation epithermal deposit types, according to the classification system of Sillitoe and Hedenquist (2003).
Gold–silver mineralization is associated with a variable assemblage of pyrite-sphaleritemarcasite-pyrrhotite ± chalcopyrite ± galena ± arsenopyrite (± stibnite ± tetrahedrite ± bismuthite). Sulphide and gangue mineralogy are reasonably characteristic of an intermediate sulphidation regime as defined by Sillitoe and Hedenquist (2003). However, the massive fine-grained silicification present at Blackwater is more typical of high-sulphidation deposits and minor carbonate gangue of a low-sulphidation environment.
Mineralization
Core drilling has defined a zone of continuous gold mineralization that extends at least 1,300 m along its longest dimension east-west and at least 950 m north–south. The vertical thickness of the zone ranges up to 600 m, remaining open at depth in the southwestern part of the deposit, as well as to the northwest and west. The center of the deposit has an average thickness of 350 m and, where open, a vertical extension of up to 600 m.
Mineralized rocks within the main Blackwater resource area can be broadly divided into a thick succession of felsic to intermediate pyroclastic and volcaniclastic rocks, volcanic flows and breccias, and related volcanic and lithic-derived sedimentary units (fine to coarse epiclastic rocks). Whole-rock analysis indicates that these units range from rhyolite to dacite to andesite in composition. Detailed age relationships between the mineralized host rocks at Blackwater are not entirely understood, but the vertical succession and locally observed progressive inter-bedding of these units suggest the andesite to be oldest, followed by the felsic tuffs and subsequently the felsic volcaniclastic rocks.
Gold–silver mineralization is associated with a variable assemblage of pyrite–sphalerite– marcasite–pyrrhotite ± chalcopyrite ± galena ± arsenopyrite (± stibnite ± tetrahedrite ± bismuthite).
Sulphide mineralization at Blackwater can be divided into three types:
- Disseminated:
- As pinhead to coarse blebby sulphide grains and aggregates typically ranging from 1% to 5% total volume of the rock, but locally exceeding this volume. Disseminations may be uniform or irregular, with sulphides displaying an anhedral to euhedral crystal form;
- Disseminations of a dark-grey, very fine grained sulphide material (DBS) is common at Blackwater and may form as fine disseminations to coarse clusters, as thicker coatings to fractures, or as an irregular network of “dendritic” micro-cracks within the rock mass;
- Porosity infill:
- Sulphides that fill, rim, or replace devitrified pyroclasts, tephra, and juvenile pumiceous material. Sulphides also commonly form parallel to compositional layering and laminations within felsic pyroclastic flows and laminated tuff units. Mineralized amygdules and altered feldspars are also observed in the andesite flow units;
- Vein:
- Polymetallic, anhedral to euhedral sulphide assemblages in sub-millimetre to centimetre- scale polymetallic veinlets–veins of quartz–sericite–chlorite–clay (illite) ± (iron) carbonate ± tourmaline ± vivianite;
- Hydrothermal brecciation and related silicification – centimeter- to metre-scale zones of hydrothermal brecciation, alteration, and elevated sulphide content. These breccia zones are typically healed with silica- sericite-sulphide cement and cut by a micro stockwork of vitric quartz ± sulphide veinlets;
- Structure-related (late?) – sulphides crushed to comminuted in brittle fault breccia and gouge.
Hydrothermal alteration (and possibly contact metamorphism) has produced several superimposed alteration assemblages, including pervasive silica–sericite–clay (illite) ± biotite alteration and veinlet/fracture-controlled silica–sericite–chlorite–clay ± iron carbonate ± tourmaline. An early (?) biotite–silica–albite ± chlorite/actinolite hornfelsing event may have been significant, although mineralization in these rocks appears to be lower than in units without evident hornfelsing. Visible native gold has been noted in some drill holes.
Five types of secondary quartz were identified:
- Pervasive, amorphous to translucent silicification with associated illite ± sericite;
- Intense silicification of felsic units, epiclastic rocks, and more intermediate volcaniclastic rocks with biotite alteration of the matrix (hornfels) identified in drill holes;
- Cryptocrystalline silica replacements in felsic ash-tuff layering;
- Silica cement/matrix to local hydrothermal brecciation;
- Sub-millimetre vitric quartz veinlets in zones of intense silicification; commonly as a microstockwork.
Gold and silver mineralization is hosted predominantly within a central core of felsic tuffs and volcaniclastic breccias that are enveloped by a sequence of massive and more- cohesive andesitic flows and tuffs. The deposit is roughly rhombohedral in plan, bounded by near vertical northwest- and northeast trending faults.