Pennsylvania; Keystone Prospects, Kantishna Mining District, Denali Borough, Alaska, USAi

Regional Level Types
Pennsylvania; Keystone Prospects	Group of Prospects
Kantishna Mining District	Mining District
Denali Borough	Borough
Alaska	State
USA	Country

The claims are in Denali National Park and Preserve.
Location: The Pennsylvania and Keystone prospects are on patented, adjacent claims in the canyon of Iron Gulch, a south-flowing tributary to Eureka Creek. The location is at the center of the end line between the two claims. It is about 150 feet west of Iron Gulch, and about 0.24 mile west-northwest of the center of section 7, T. 16 S., R. 17 W., Fairbanks Meridian. The location is accurate within 300 feet. The prospects are number 30 of Bundtzen (1981) and 39 of Thornsberry, McKee, and Salisbury (1984), and are included in location 12 of MacKevett and Holloway (1977).
Geology: The area of the Pennsylvania-Keystone claims is underlain mainly by 'quartz-eye' metafelsite of the Spruce Creek sequence (Thornsberry, McKee, and Salisbury, 1984, fig. K-2; v. 2 occurrence 39; Hawley and Associates, 1978, fig. 4.1-(A)1). The claims are close to the axis of the Kantishna antiform (see record MM091). Two main veins, the Pennsylvania and the Keystone, have been explored on the claims. The Pennsylvania vein crosses the west end line of the Pennsylvania claim about 100 feet north of the center of the claim. The vein strikes N 65 E and dips 85 S. It continues easterly (uphill) for about 500 feet and strikes toward the Pittsburgh vein (MM109), with which it probably correlates (Davis, 1923, p. 129; Thornsberry, McKee, and Salisbury, 1984, v. 2, no. 39). The Keystone vein is about 100 feet south of the Pennsylvania vein at the west end of the Pennsylvania claim. It strikes about N 50 E, and dips 60 S. The Keystone vein continues southwest for about 800 feet on the Keystone claim, and intersects the Pennsylvania vein on the Pennsylvania claim. Its total strike length is at least 1200 feet. A third vein, which crops out between the Pennsylvania and Keystone veins, appears to intersect both of the them (Davis, 1923, p. 130), and a fourth vein is suggested by quartz float near the north boundary of the claims (Thornsberry, McKee, and Salisbury, 1984, v. 2, no. 39). The Pennsylvania vein consists mainly of quartz and calcite, and contains pyrite and free gold. The Keystone vein consists mainly of quartz, along with arsenopyrite and pyrite and lesser amounts of galena and sphalerite (Capps, 1919, p. 122-23). Spectacular dendritic gold occurred in a shallow pit on a thin quartz vein that may be part of the Keystone vein (Capps, 1919; Davis, 1923, p. 130; Moffit, 1933, p. 131-132). Other minerals in the veins include chalcopyrite, scorodite, jamesonite(?), tetrahedrite, and scheelite (Bundtzen, 1981; Thornsberry, McKee, and Salisbury, 1984).
Workings: The veins were explored by numerous open cuts, short adits, and shafts, currently (2001) mostly inacessable. Considerable development occurred prior to 1922 (Davis, 1923), and a little work was done in subsequent years. In 1983, the U.S. Bureau of Mines drilled three diamond core holes (K-8, -9, and -10). Between 132 and 135 feet, drill hole K-8 intersected vein quartz, chalcedonic quartz and dolomite, and mineralized metafelsite. Core recovery was only fair, and one section was lost. The best intersection was 147 to 150 feet, which assayed 0.294 ounce of gold per ton and 0.276 ounce of silver per ton. From 34.5 to 43.5 feet, drill hole K-9 intersected quartz-dolomite vein material and possible stope fill that assayed 0.10 ounce of gold per ton. Hole K-10 intersected quartz-dolomite-ankerite(?) vein material containing traces of gold and silver. Drill hole K-8 probably intersected the Pennsylvania vein (Thornsberry, McKee, and Salisbury, 1984, v. 2, occurrence 39 and drill logs).
Age: The deposit is assumed to be Eocene (see record MM091).
Alteration: Oxidation of arsenopyrite to scorodite.
Production: Production is unknown but small quantities of dendritic gold were almost certainly taken from the claims.

Commodities (Major) - Au; (Minor) - Ag, Cu, Pb, W, Zn
Development Status: Undetermined.
Deposit Model: Low-sulfide gold-quartz vein (Cox and Singer, 1986; model 36a).

Other Databases

Link to USGS - Alaska:	MM116

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References