Summary:
The Ruby Hill Project is located along the southeastern end of the Battle Mountain/Eureka gold trend. The Eureka gold mining district exposes a nearly continuous sequence of Cambrian and Ordovician sedimentary rocks approximately 10,000' thick consisting of primarily carbonate units with subordinate shale and quartz sandstone.
Mineralization at Ruby Hill is characterized by early polymetallic, intrusive-related carbonate replacement and skarn deposits that have been overprinted by younger Carlin-type precious metal mineralization.
Within the Property area, two styles of mineralization occur:
• Early polymetallic (Au-Ag-Pb-Zn) skarn or carbonate replacement deposit (CRD): Blackjack and TL).
• Late Au±Ag Carlin-type: East Archimedes, West Archimedes, 426, Ruby Deeps, Mineral Point zones.
The polymetallic skarn and CRD style is the oldest mineralization event recognized at the Property and related to emplacement of the Cretaceous intrusive units. The precious metal-rich Carlin style overprints the older CRD event and interpreted to have developed during early-middle Cenozoic (Eocene) times, similar to other Au-Ag deposits of the Battle Mountain/Eureka Trend. Mineralization is largely controlled by lithology and structure.
Gold-silver mineralization occurs broadly as a near N-trending zone (Mineral Point Trend), consisting of smaller zones of structurally and lithologically controlled deposits (East and West Archimedes, 426, Ruby Deeps, Mineral Point, Achilles, and Hector). Mineralization, both Au-Ag and Au-Au-Pb-Zn is primarily hosted within the Windfall and Goodwin Formations, and within the Hamburg Dolomite. Combined mineralization spans an area approximately 12,000 ft long, 9,000 ft wide, at the maxima, and spans from surface to approximately 2,400 ft below surface.
Mineralization is focused along high- and low-angle faults, lithologic contacts, fold axis, and sanded plus breccia zones.
Gold occurs as free grains within the oxide portions along with iron oxides, and associated with sulfide minerals (pyrite, arsenopyrite, arsenian pyrite, realgar, and orpiment) within the unoxidized portions of the deposits. Within the oxide horizons, petrographic work for samples from the Archimedes deposits “…indicate(s) that the gold was originally associated with pyrite grains, with no evidence of silica encapsulation. Higher grade gold mineralization occurs in zones of jasperoid and decalcified limestone,” (Resource Evaluations Inc., 2005).
Mineral Point Trend Geology and Mineralization
The Mineral Point Trend deposit consists of gold and silver mineralization hosted by the Cambrian Hamburg dolomite in the nose of a broad anticline that plunges to the northnortheast and is bound to the east by the Holly Fault and to the west by the West Fault. The Mineral Point Trend is 9,000 ft long, 2,400 ft wide and up to 500 ft thick. The top of the Mineral Point Trend is near surface at its south end and 500 ft below surface at its north end. Majority of the mineralization in the Mineral Point Trend deposit is oxidized and has a high ratio of cyanide soluble to fire assay total gold. This deposit has not been mined and is the largest precious metal Mineral Resource in the Ruby Hill Project.
West Archimedes Geology and Mineralization
The West Archimedes deposit is hosted in the Ordovician Upper Goodwin limestone unit and is bound to the west by the Holly Fault. The zone strikes north-west and dips shallowly to the north-east. The deposit measures 2,000 ft along strike and 740 ft down dip and is up to 300 ft thick. The majority of West Archimedes was mined in an open pit before mining at East Archimedes. The mineralization in the West Archimedes deposit is oxidized and has a high ratio of cyanide soluble to fire assay total gold.
East Archimedes Geology and Mineralization
The East Archimedes Zone occurs east of the Graveyard Fault and proximal to the Graveyard Stock. Mineralization extends eastward from the West Archimedes Zone in the Upper Goodwin Formation and extends downward in the Lower Laminated and Lower Goodwin units along the contact with the Graveyard Stock. Silver and base metal grades are elevated in the East Archimedes zone in comparison with the other zones in the Ruby Hill Project in an envelope around the Blackjack zone replacement-style zinc mineralization described below. Mineralization in East Archimedes is roughly 1,200 ft wide and 1,200 ft long in plan and extends from surface where it is well defined by shallow drilling to several mineralized intersections over 1,800 ft below surface. The upper portion of the East Archimedes deposit, above an elevation of approximately 5,000 ft, is oxidized and transitional oxide-sulfide mineralization with a high ratio of cyanide soluble to total fire assay gold. The upper portion of the East Archimedes zone has been mined from surface.
426 Zone Geology and Mineralization
The 426 zone occurs in the Lower Laminated unit of the Goodwin Formation and the upper part of the underlying basal Goodwin unit of the Goodwin Formation in the nose of a fold. The mineralized zone forms a rod-shaped body plunging shallowly to the northeast that is 1,400 ft long, 200 ft wide and 200 ft thick. The top of the zone is approximately 1,000' below surface, but it is 500' below the bottom of the current East Archimedes pit bottom. Majority of the higher-grade mineralization occurring in the Goodwin Formation Lower Laminated unit is sulfide-style mineralization with a low ratio of cyanide soluble to total fire assay gold but the lower portion of the zone that is hosted in the basal Goodwin Unit has a moderate cyanide soluble to total fire assay gold mineralization.
Ruby Deeps Zone Geology and Mineralization
The Ruby Deeps zone is a north-northeast striking, shallowly east dipping zone of mineralization hosted in the Windfall Formation in proximity to bodies of Bullwhacker Sill intrusive bound by the Graveyard Fault to the east and the Holly Fault to the west. The zone is 2,400 ft long 500 ft wide and 600 ft thick. The top of the zone is 1,600 ft below surface and 1,000 ft below the bottom of the West Archimedes pit. Within the zone there are several tabular horizons of higher-grade mineralization that are 40 ft to 100 ft thick.
Blackjack Zone Geology and Mineralization
The Blackjack zone is a pod of replacement style zinc mineralization hosted by the Lower Goodwin Unit directly in contact with the Graveyard Stock within the East Archimedes Zone. Mineralization occurs as a pod of sphalerite mineralization with elevated lead, copper, and silver. The base metal-rich carbonate replacement style mineralization has been overprinted by later Carlin-style gold mineralization. The Blackjack zone measures approximately 500 ft wide, 500 ft long, and 950 ft high. The upper part of the Blackjack zone is partially oxidized with a high-to-moderate ratio of cyanide soluble to total fire assay gold, but sphalerite is un-oxidized. The lower portion of the zone is un-oxidized.