Blueberry

Prospect, Active

Commodities and mineralogy

Main commodities Cu
Other commodities Mo
Ore minerals chalcopyrite; molybdenite; pyrite
Gangue minerals biotite; chlorite; hornblende; sericite

Geographic location

Quadrangle map, 1:250,000-scale RM
Quadrangle map, 1:63,360-scale A-5
Latitude 61.0691
Longitude -160.0637
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is on the southwest flank of the ridge on the west side of Sabula Creek. It is located about 0.1 mile northeast of peak 'Granite', about 0.5 mile west-southwest of the center of section 2, T. 11 N., R. 60 W., of the Seward Meridian. This location is accurate to within 1000 feet of the center of the prospect.

Geologic setting

Geologic description

The Blueberry prospect comprises disseminated sulfide minerals in sericite- and chlorite-altered hornblende-biotite granite intruded into Cretaceous hornblende-biotite granodiorite of the Nyac Batholith. Mineralized rock has dominantly coarse-grained seriate to porphyritic textures and less abundant fine grained granular to quartz phyric (porphyry) and aplite. Distinctive features of the mineralized rock include common aquamarine-colored (blue-green) sericite-altered plagioclase phenocrysts in coarse-grained seriate and porphyritic varieties and chlorite alteration of biotite and hornblende. Sulfide minerals include pyrite, chalcopyrite and molybdenite. Chalcopyrite is far more abundant than molybdenite, but the fine-grained textural variety tends to be enriched in molybdenite relative to chalcopyrite. Molybdenite also appears to be more abundant in weakly altered coarse-grained granite distal from the more strongly altered and mineralized core. In some cases, the disseminated sulfide minerals are concentrated in altered hornblende crystals. These rocks and the finer aplite and quartz porphyry tend to be unusually hard and difficult to break, even with sledge hammers. The finer-grained varieties are commonly found at the margins of the mineralized surface exposure (Foley, 2011).
Soil samples collected and assayed in 2010 from several sites adjacent the Blueberry prospect have elevated copper and molybdenum values. It is anticipated that additional concentrations of sulfide minerals might be found in this area with additional prospecting (Foley, 2011).
Preliminary IP and resistivity plots show anomalies in the vicinity of the Blueberry prospect. Where shallow, these anomalies are coincident with observed sulfide minerals in altered rocks similar to those described in the core of the prospect. Furthermore, the preliminary plots indicate that the feature plunges to the east, and extends for approximately 1600 meters east to west (Foley, 2011).
It has been suggested that the physical properties of the mineralized rock, perhaps because of silicification that causes the unusual hardness, may explain the resistive characteristics as indicated by the preliminary data. It is further surmised that the relatively low sulfide content may account for the low to moderate IP signature of the feature (Foley, 2011).
Geologic map unit (, )
Mineral deposit model Unknown.
Age of mineralization Younger than the Cretaceous host granodiorite of the Nyac Batholith that the mineralized granite is intruded into (Foley, 2011).
Alteration of deposit Sericite-altered plagioclase, chlorite-altered biotite and hornblende. Molybdenite appears more abundant in the weakly altered zones (Foley, 2011).

Production and reserves

Workings or exploration
Nyac Gold LLC operated summer exploration programs in 2010 and 2011 at Blueberry Prospect on behalf of Calista Corporation focused on prospecting and sampling (Foley, 2011; Flanders and others, 2011). In 2011, Zonge International conducted a geophysical field survey including acquisition of both gradient and pole-dipole array resistivity and induced polarization (IP) data. The objective of the geophysical program was to provide information on the distribution and occurrence of sulfides associated with poly-metallic mineral deposits (Zonge International, 2011).
In 2010, soil samples were collected and assayed; values for copper and molybdenum were elevated. The surface extent of exposed mineralized rock measured about 230 feet along the north-south axis and about 500 ft along the east-west axis. One result of the 2011 program was to the discovery of additional mineralized rock found outward of the core area at several sites. The presence of elevated copper and molybdenum values detected in soil samples at several sites outside the Blueberry prospect suggests that additional concentrations of sulfide minerals might be found with additional prospecting (Foley, 2011).
Indication of production Undetermined
Reserve estimates None.
Production notes None.

References

References

Flanders, Richard, Mataresse, Maia, Bethe, Mike, 2011, 2011 Drilling and Exploration for Lode Gold Deposits in the Nyac District, Southwest Alaska 36 p. (Report held by Calista Corporation, Anchorage, Alaska).
Foley, Jeff, 2011, Blueberry Prospect Provisional Summary, Unpublished Internal report for Calista Corporation, 3p. (Report held by Calista Corporation, Anchorage, Alaska).
Zonge International, Inc., 2012, Gradient and IP and Pole-Dipole Complex Resistivity Geophysical Survey, Blueberry Project, Nyac, Alaska, for Calista Corporation, 30 p. (Report held by Calista Corporation, Anchorage, Alaska).
Reporters V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 12/20/2014