| |
Atna's wholly-owned subsidiary Seven-Up Pete Venture ("SPV") controls the majority of the Columbia Gold Mine mineralization.
The Columbia Mine property is located seven miles east of Lincoln and 45 miles northwest of Helena, in Lewis and Clark County, Montana. Access to the property is by a paved highway that crosses through the property. Seven-Up Pete consists of approximately 14 patented and 74 unpatented mining claims. The patented claims are subject to NSR royalties that range from 2.5% to 6%. Discussions are being held with the owners of part of the mineral interest on the property for the purposes of consolidating the property.
Between 1989 and 1993, exploration, bulk sampling, development studies, metallurgical testing, and environmental baseline studies were conducted on the Seven-Up Pete property. By 1993, the total drilling on the property was 378 holes totaling 159,410 feet of drilling. In addition, some 8,000 feet of surface trenching was completed. A preliminary feasibility study was completed in January 1993, updating an earlier 1991 study.
The earlier studies utilized cyanide based gold recovery systems. State law currently prohibits the use of cyanide in Montana. Consequently, Atna is reviewing gold recovery by conventional gravity and froth flotation recovery methods on bulk samples from the mineralized zone. Initial results are promising and additional test work is required to determine if this process is economically viable. A feasibility study at the Seven-Up Pete would include metallurgical test work and an Environmental Impact Study to obtain permits.
The Columbia Mine property is covered by middle Tertiary andesitic volcanic rocks. The most prominent controls on mineralization at Seven-Up Pete are north to northwest-trending faults that have localized quartz-pyrite-precious metal mineralization. The structures generally dip to the west and can be up to 150 feet wide. Gold and silver occur in high grade quartz veins that are localized near the margins of the shear zone, as well as in lower grade shattered zones between the high grade veins. Gold mineralization occurs as free gold as well as submicroscopic particles associated with pyrite. A 2006 study performed utilizing the 1993 feasibility study mineral model without validation, indicates that unconstrained, non NI-43-101 Compliant mineralized material associated with Seven-Up Pete controlled property totals 17 million tons at an average grade of 0.035 ounces of gold per ton at a cutoff grade of 0.02 opt gold. This cutoff grade may be reflective of an appropriate cutoff grade for an open pit mine with a conventional grind/gravity/flotation recovery process.
| |
