Jan 4 2016
Comstock Mining Inc. is pleased to provide an update on the Lucerne underground exploration and underground drift development. The Company recently announced it had completed the entire 800-foot underground exploration drift at the north end of the existing surface mining operation.
Figure 1 - 3D representation of underground drifting, drill bays, crosscut and drill traces
The Harris Portal runs parallel to the previously discovered dike-like masses of quartz porphyry (PQ) that have intruded into the main lode.
Corrado De Gasperis, President & CEO, commented, "Our teams have now completed the targeted 800 foot segment of the Lucerne exploration drift, plus expanded the drift an additional 200 feet towards the historic Succor vein system and also completed approximately 10,000 feet of diamond core drilling. We have also begun receiving assay results and look forward to reporting on these drill results over the next few weeks and throughout January and early February."
The Company's transition from Lucerne's open cut mining toward underground exploration and development (Harris Portal and tunnel) marks a significant turning point for the Company. The Lucerne Drift represents the first substantial underground development in the Comstock District in over 30 years. The tunnel, when complete, is designed to conduct an underground exploration drilling program directed at a series of geological targets in the Silver City Branch of the Comstock Lode, including the PQ target, the Succor vein systems and the historic Woodville Bonanza system. These initial targets represent the core of a broader geological corridor where the Company is currently drilling. Previous surface drilling in the area, including the Succor-Holman drilling from earlier this year, had suggested that a zone lying generally adjacent to and below the Lucerne Cut had the potential to yield high-grade gold and silver. The current program has been geared toward defining that potential.
The Harris tunnel was driven in a northwest direction within the most stable footwall rocks. As of December 30, 2015, the total length of drifting is approximately 1,150 feet, including six drill bays and an approximately 200 foot long crosscut, out of Bay 2, into the veined system. Figure 1 (link below) depicts the underground drifting and drilling as completed thus far.
As of December 30, 2015, approximately 10,000 feet of diamond core drilling has been completed from the six drill bays. Drilling takes the form of 'fans' that comprise a group of holes having the same azimuth but different dips (between -50 and plus 40 degrees from horizontal). Each drill bay has two or three fans of drill holes extending into the primary target, and in some cases to the Succor mineralized zone. The core locations and orientations were designed to expand areas of known high-grade mineralization identified from past surface drilling programs.
The drilling to date has been either HQ3 or NQ core, and high-polymer muds are routinely employed to enhance core recovery, which to date, has been excellent. The planned core-portion of the program will conclude in late January 2016, with total estimated core drill footage of approximately 12,000 feet. The Company is planning an additional 10,000 feet of reverse circulation (RC) drilling, in early 2016, in portions of the PQ target area plus some surface drilling to better scope the extents of the Succor structure.
The Company remains on schedule to complete the first phase of the portal, drift, drilling, and evaluation of these results by early February. Assay results, geological interpretations and context will be forthcoming throughout January 2016.
Corrado De Gasperis concluded: "We are focused on this transition to higher-grade targets as we conclude the production for Lucerne in 2015, including the completed SR 342 realignment. We ended the year with good gold and silver grades, the lowest costs in our history, and exceptional final gold and silver yields, as our life of mine recoveries for Lucerne gold yields rose to an estimated 84-85%, from a previous 81%. This positions the platform and the district well for our future growth plans."