The DDGM area is predominantly volcanic rocks of presumed Miocene age, which overlay and intrude into basement rocks consisting of marine sediments. This district's gold and silver mineralization is related to the volcanogenic system and is considered epithermal in character. The DDGM mineralization occurs as structurally controlled epithermal deposits in veins and stockwork zones. The mineralization is associated with gangue minerals such as quartz, calcite, and other minor elements. Primary sulfide mineralization consists of pyrite galena, sphalerite, chalcopyrite, and different minor amounts of argentite and silver sulfosalts. It consists of concentrations of sulfides containing gold, silver, lead, copper, and zinc.

DDGM exploration efforts have been mainly focused on the Arista Project, which contains the Manto Vein, Arista, and Switchback vein deposits, and includes the significant Arista, Baja, and Soledad veins as well as multiple ancillary structures. The principal hosts of mineralization are the Arista and Switchback vein systems, known from drilling and underground workings in the Arista underground mine. The Switchback deposit is approximately 500 m northeast of the Arista deposit. Both vein systems are andesitic host rocks, rhyolite dikes, and structural contacts with the basement sedimentary rocks. The mineralization in these systems is intermediate sulfidation with precious and base metals at economic grades. Both vein systems trend northwesterly; alt ........

Substantial development was undertaken from 2010-2011 to access the Mineral Resources of the Arista vein system and to provide ancillary access for further exploration and development. In addition, a significant amount of mining on the Arista vein system was achieved to determine the “mineability” of the orebody and to optimize an extraction method(s) for mining the mineralized zones. The principal exploration access and haulage decline ramp were opened at surface positioned along Aire Creek. The portal opening is located at an elevation at 902 (masl) accessing the mineralized area of the Arista vein system. The decline was driven as a spiral with a minus 10 percent grade in the footwall of the mineralized area. Underground mine planning and exploitation is based on a typical vertical separation of mine levels of approximately 20m.

To date, DDGM has advanced the primary decline ramp down to Level 28, approximately 4,400 meters ramp distance from the mine portal. DDGM has also constructed a safety/ventilation decline ramp in conjunction with the primary decline ramp along with various drifts, raises and stopes encompassing approximately 500 m vertically and 1,300 m along strike length.

There are two main mining methods used in the Arista mine: 1) overhand mechanized cut and fill (CAF) and 2) long-hole open stoping (LHOS) with delayed fill. Paste fill, cemented rock fill and uncemented rock fill are applied to long-hole stoping areas in order to increase ........

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