Copper King Property Update
ELKO, NV - U.S. Gold Corp. reported an overall update on its Copper King property located in the Silver Crown mining district of southeast Wyoming, approximately 20 miles west of the city of Cheyenne, on the southeastern margin of the Laramie Range. The property comprises about 1,120 acres that include two Wyoming State Mining Leases covering the S½ Section 25, NE¼ Section 35 (lease# 0-40858), and all of Section 36 (lease# 0-40828), T14N, R70W, 6th PM, Laramie County, Wyoming.
Limited exploration and mining were conducted on the Copper King property in the late 1880s and early 1900s. Approximately 300 tons of material was reported to have been produced from a now inaccessible 160-foot-deep shaft with two levels of cross-cuts. A few small adits and prospect pits with no significant production are scattered throughout the property.
Since 1938, at least nine historic (pre-Strathmore) drilling campaigns by at least seven companies plus the U. S. Bureau of Mines (USBM) have been conducted at Copper King. The current project database contains 91 drill holes totaling 37,500 feet that were drilled before U.S. Gold Corp. acquired the property. All but six of the drill holes are within the current resource area. Other work conducted at Copper King by previous companies has included ground and aeromagnetic surveys, as well as induced polarization (IP) surveys along with geochemical sampling, geologic mapping, and a number of metallurgical studies.
Wyoming Gold conducted an exploration drill program in 2007 and 2008. Thirty-five diamond core drill holes were completed for a total of 25,500 feet. The focus of that work was to confirm and potentially expand the mineralized body outlined in the previous drill campaigns, increase the geologic and geochemical database leading to the creation of the current geologic model and resource estimate, and to provide material for further metallurgical testing. The Copper King assay database for some 120 holes contains 8,357 gold assays and 8,225 copper assays. At least 10 different organizations or individuals conducted metallurgical studies on the gold-copper mineralization at the request of prior operators between 1973 and 2009. It was concluded that the process with the highest potential to yield good extractions of gold and copper would likely be flotation, followed by cyanidation of the flotation tailings.
The Copper King Project contains 59.75 million tons of measured and indicated mineral resources with average grades of 0.015 ounces/ton Au and 0.187% Cu, containing approximately 926,000 ounces of gold and 223 million pounds of copper. In addition, the Copper King Project contains approximately 15.62 million tons of inferred mineral resources with average grades of 0.011 ounces/ton Au and 0.20% Cu, containing 174,000 ounces of gold and 63 million pounds of copper.
The Copper King project is underlain by Proterozoic rocks that make up the southern end of the Precambrian core of the Laramie Range. Metavolcanic and metasedimentary rocks of amphibolite-grade metamorphism are intruded by the ~1.4 billion year old Sherman Granite and related felsic rocks. Within the project area, foliated granodiorite is intruded by aplitic quartz monzonite dikes, thin mafic dikes, and younger pegmatite dikes. Shear zones with cataclastic foliation striking N60°E to N60°W are found in the southern part of the Silver Crown district, including at Copper King. The granodiorite typically shows potassium enrichment, particularly near contacts with quartz monzonite. Copper and gold mineralization occurs primarily in unfoliated to mylonitic granodiorite. The mineralization is associated with a N60°W-trending shear zone and disseminated and stockwork gold-copper deposits in the intrusive rocks. Some authors have categorized it as a Proterozoic porphyry gold-copper deposit.
Hydrothermal alteration is overprinted on retrograde greenschist alteration and includes a central zone of silicification, followed outward by a narrow potassic zone, surrounded by propylitic alteration. Higher-grade mineralization occurs within a central core of thin quartz veining and stockwork mineralization that is surrounded by a zone of lower-grade disseminated mineralization. Disseminated sulfides and native copper with stockwork malachite and chrysocolla are present at the surface, and chalcopyrite, pyrite, minor bornite, primary chalcocite, pyrrhotite, and native copper are present at depth. Gold occurs as free gold.
Several historical geophysical techniques have been tried on the Copper King property. U.S. Gold Corp. has the historical data including a ground magnetic survey done in 1997. The known deposit mineralization correlates directly with a strong magnetic anomaly rising in excess of 400nT over background. Historical drilling confirmed the anomaly to be produced by magnetite which correlates well with known mineralization. Historic reports make the observation that two other anomalies to the east and southeast are similar in character to the one associated with mineralization and identifies these as exploration targets. It is unclear if these were ever drill tested in the past.
The ground magnetic survey agrees with earlier magnetic work and defines a complex lithologic / structural setting with two major fault sets. The north-south set is a major feature related to the eastern range front of the Laramie Mountains. Numerous magnetic anomalies, with character similar to the magnetic response of the Copper King mineralization, are offset by the structures. An obvious northwest extension of the magnetic response at the Copper King mine appears to not have been explored. This is considered a prime exploration target.