Location and History
The North Fork project is in the Alleghany mining district in the northern part of the Mother Lode Gold Belt in northeastern California, 35 km northeast of Grass Valley and about 3.5 km northwest of the Sixteen-to-One mine.
Property
North Fork Mining Corp., and wholly-owned subsidiary of Bullion River Gold Corp., controls 42 unpatented mining claims through a lease agreement.
Geology and Mineralization
The Alleghany mining district is within the northern portion of the Mother Lode Belt and on the north side of the Grass Valley mining district. Gold mineralization within the Mother Lode Belt occurs along the regional, northerly-trending Melones fault system following the western flank of the Sierra Nevada Range. The belt has a strike length of more than 300km and averages about 80km in width. Gold deposits occur as mesothermal, quartz-carbonate vein systems along faults within metamorphic rocks. Gold occurs in free form commonly with arsenopyrite. The Grass Valley and Alleghany districts are notable for their high gold grades and for the largest gold production among all mesothermal vein camps in western North America.
The North Fork property is along the strike extension of the prolific gold-bearing quartz veins in the Alleghany area about 3 km to the southeast. At North Fork, data from historic underground examinations indicate a 240m wide zone containing steeply-dipping gold-bearing quartz veins locally exceeding 6m in width. Assays grading above 0.5 opt (15 g/t) Au are common and nearly continuous along the approximately 600 feet of vein-parallel drifting on 3 levels covering about 50 meters vertically. Grades exceeding 1 opt are also common. Gold veins and their host rocks in the district are capped by post-mineralization volcanic rocks, creating opportunities to discover additional concealed mineralization.
Previous Work
Placer gold was discovered in the Mother Lode Belt in 1849 and in the Alleghany district in 1852. Underground mining of high-grade veins at Alleghany began in 1853. The North Fork Mine was developed between 1875 and the 1930’s with a 13-degree decline about 1,000 feet long, then an 800 foot long crosscut connecting to a 60 degree inclined shaft from which three levels were developed. All three levels intersected significant gold grades commonly exceeding 0.5 opt Au along multiple veins. Based on the historic assays, there is an inferred resource of 100,000 tons grading at least 0.5 oz/ton grade; however, additional exploration drilling is necessary to develop a mineable reserve. Subsequent to the 1930’s, some of the underground workings collapsed, and the lower portion of the mine was flooded. A number of other historic mines exist on the property, and some have recorded production from high-grade veins.
Opportunities
Given the high gold grades at North Fork, the limited development, the reported widths of the veins, and its location along strike with major gold vein systems at nearby Alleghany, the project has excellent potential for the discovery of new high-grade reserves amenable to underground mining. There has been no systematic modern exploration on the property.
Future Plans
The North Fork Mining Corp. established on-site infrastructure at the North Fork mine in 2004 and began rehabilitation of this historic decline. In the future, one or more underground drill stations will be constructed and a drilling program planned to test the vein system. The goal of the drilling program is to establish an initial geologic resource of high-grade (>0.5 opt) mineralization. If this exploration program is successful, additional drilling and underground development will be warranted. Targets in this area can be significant given that the nearby Sixteen to One Mine produced over one million ounces.