Summary:
The Gold Road deposit is interpreted to be a low-sulfidation, epithermal vein deposit, consisting mostly of quartz with local concentrations of calcite and adularia. Gold and silver are the only valuable elements which exist on an average ratio of approximately 1:1. The Gold Road vein system is exposed on the surface for approximately 1.5 miles (2.4 km).
Ore has been extracted from the Gold Road vein system for a total horizontal distance of 7,000 ft (2,133 m) and for a total vertical distance of 1,450 ft (442 m). Individual ore shoots (lodes) on the Gold Road vein structure are up to 2,100 ft (640 m)in length, 620 ft (190 m) in height and vary in width up to 20 feet (sometimes in multiple, parallel structures).
The mineralization at the Gold Road Mine consists of quartz-calcite-adularia veins within the northwesttrending Gold Road fault zone. The fault zone can be over 150 ft (46 m) wide and quartz vein(s) may occupy one or more strands within the structure. Vein strands usually occupy the footwall, hanging wall or a central portion of the structure, but strands may occur in two or all three of these positions within the same area. Where the fault zone is narrow (such as areas within the Gold Road latite) vein material may occupy the entire structure.
The “main” Gold Road vein occupies a strong fault fissure, typical of the district. This structure was formed by several separate movements before, during and after gold mineralization. The strike of the sinuous vein varies from N50°W to N66°W and generally dips 65° to 85° to the northeast, though locally the vein can be vertical or dip steeply to the southwest. The vein system crops out continuously for about 7,500 ft (2,286 m) on the Property, including a segment that is in ore grade mineralization on the surface for over a mile (1,524 m). Most of the ore has been mined in wide lenses within dilatant zones of the vein structure. The wider dilatant zones of the vein may be related to areas of north- to northeast-curving concavity along the sinuous normal fault.
The character of the Gold Road vein varies considerably along its vertical extent. In the lowest stratigraphic exposures, the vein consists of fine-grained chalcedonic and banded quartz in a braided or complex stockwork vein system up to 30 ft (9 m) wide hosted in Oatman latite. At stratigraphically higher exposures where the vein is hosted in Gold Road latite, the vein is a tabular, fissure-like body typically 3-7 ft (0.9-2.1 m) wide. Historically, high-grade ore has only been mined from the Gold Road vein within Oatman latite and Gold Road latite. At the highest exposed levels, the Gold Road vein cuts lithologies of the Upper Volcanics series (Sitgreaves Tuff and Antelope quartz latite). This upper zone generally coincides with the Red Top prospect area. Mineralization at Red Top consists of very fine grained chalcedonic quartz and siliceous sinter deposits reflective of the uppermost levels of a low-sulfidation epithermal system, near the paleosurface or paleo-water table. Quartz mineralization at Red Top is several inches to a foot (0.3 m) wide and does not contain significant gold mineralization. Although the character of Gold Road vein varies depending on host rock, the changes in the vein at formation contacts are not sharp and abrupt. There is a gradual narrowing of the vein system upward.
The mineralogy of the Gold Road vein is typical of the district. The deposit is interpreted to be a lowsulfidation, epithermal vein deposit. The vein consists mostly of quartz with local concentrations of calcite and adularia. At least five major stages of quartz deposition are present in the vein. The last two stages of quartz, which consist of pale green to deep honey yellow, fine- grained chalcedonic silica and breccia, appear to have accompanied most of the ore grade gold in the vein.
Gold is the most valuable constituent of the ore at the Gold Road Mine. Silver occurs with the gold in a ratio of approximately one part gold to one part silver on average. Sulfides are rare in the ore, but do occur in higher grade shoots. Fluorite is locally present. High-grade ore frequently contains very fine-grained free gold, copper sulfides or carbonates and, rarely, cerargyrite (AgCl) in thin quartz bands. Most gold is microscopic.