Miller Mountain Gold Project

Miller Mountain Mining District, Boise County, Idaho

HIGHLIGHTS

• Epithermal and orogenic gold exploration project covering a 7.5 kilometers strike length in Idaho’s Trans-Challis fault zone
• 238 unpatented mining claims (4,920 acres) including two historic mines Specimen and Miller (Magnolia) and numerous residual and alluvial placer workings
• Multiple high-grade rock samples with up to 27 g/t gold
• Historic drilling intercepts to 7.3 metres at 21.5 g/t gold

LOCATION

The Miller Mountain project is located in the Boise National Forest approximately 5 km northeast of Lowman Idaho and northeast of the historic Boise Basin mining district. Access is via state route 21 and maintained forest service roads and ATV tracks. Elevations range from 5000 to 8000 feet. 

HISTORY

Zacapa acquired the Miller Mountain project from EMX Royalty Corp via option agreement, which was fully executed in January 2022. Prior operators in the area included U.S. Antimony Corp. (USAC), New Cinch Uranium Ltd., Tundra Gold Mines Ltd., and Westgold. USAC conducted a small (50 t/day) open pit test mining operation in 1989 that averaged 2.64 g/t Au and 1.86 g/t Ag at the Specimen mine. The test was unsuccessful due to the low gold price ($381/oz) and high trucking costs to the company mill 85 miles away. A 1984 U.S. Bureau of Mines report estimates the Specimen and Miller (Magnolia) mines contain 22.4 kt at 12.1 g/t Au, and >1 Mt at 2.2 g/t Au respectively (>79.4 koz). They also indicate that the near the top of Miller Mountain are likely to be underlain by “a large system of gold-bearing veins and fractures” and that “a gold-bearing vein deposit similar to that at the nearby Miller mine can be expected to be present at depth.”

GEOLOGY

Regional Geology

The project area is underlain by granitic rocks of the Mesozoic-age Idaho batholith that are intruded by younger Tertiary-age granitic to dioritic plutons, and by andesitic and pegmatite dikes. The area is transected by Idaho’s Trans-Challis fault zone, a large NE-SW trending regional fault system, consisting of a broad zone of northwest-trending fractures that are the locus of many of the gold deposits of central Idaho.  

Local Geology

Specimen

The Specimen mine area consists of limonitic, kaolinized, silicified, and sericitized granodiorite within two poorly-exposed shear zones, each approximately 60 meters thick. A number of smaller shear zones also parallel the two principal zones. The north shear is more highly mineralized and is composed of gouge and breccia with lenses of sugary quartz containing pyrite and visible gold. 

Miller (Magnolia)

The Miller mine area involves an approximately two meter wide east-west striking subvertical vein and number of smaller parallel veins associated with a gouge filled fracture zone in kaolinized granodiorite. The principal vein contains drusy, brecciated quartz with hematite, pyrite and visible gold. The vein is offset by a small northeast striking, steeply dipping, fault zone which is transected by an andesite dike that also contains pyrite and gold, with historic grab samples averaging 6 g/t Au.  

Mineralization

Gold-bearing structures consist of quartz-sulfide stockwork veins and discrete silicified zones associated with weak to moderate sericitic-chloritic alteration.  These vein and alteration assemblages form two distinct target types: 1) bulk tonnage, disseminated gold mineralization associated with near surface, quartz-sulfide veins and silicified zones and, 2) higher-grade quartz vein-hosted gold zones.

Geologic Model

Gold-bearing vein systems in the area display epithermal and orogenic affinities, with veins in the project areas dominantly displaying epithermal characteristics. However, locally >50 meter wide gold-bearing quartz veins have been observed that are more characteristic of orogenic systems.

EXPLORATION TARGETS

• Specimen Mine – drilling planned and permitted to pursue known shear zone hosted gold mineralization along strike and at depth
• Miller Mine – advancing drill permits to test known gold-bearing vein system along strike and at depth
• Badger (residual placer) – gold accumulations at the base of weathered bedrock associated with gold bearing veins and fractures beneath thin cover. Sampling program planned to vector toward major veins that sourced residual gold
• Quartz Hill – large 50 meter wide quartz vein with locally elevated gold values
• Specimen West – gold and arsenic soil anomaly in need of follow up mapping and sampling
• Spur 2 – gold and arsenic soil anomaly in need of follow up mapping and sampling

PERMITTING AND ESG

• Baseline water sampling initiated and continuing
• Plan of Operation Permits approved by USFS for up to 12 holes from eight pad locations at Specimen mine area. 
• Plan of Operation Permits for Miller (Magnolia) mine area under review by USFS for up to 12 holes from seven pad locations. 

REFERENCES

Close, T.J., 1993, Mineral Resources of the Red Mountain Roadless Area, Boise, Custer, and Valley Counties, Idaho: U.S. Department of the Interior, Bureau of Mines, Mineral Land Assessment Open File Report MLA 4-93, 132 p.