Broken Shovel

Prospect, Active

Commodities and mineralogy

Main commodities Ag; Au
Other commodities As; Cu; Pb; Sb; Zn
Ore minerals arsenopyrite; gold; lead-antimony sulfosalts; scheelite; tetrahedrite
Gangue minerals dolomite; quartz; tourmaline

Geographic location

Quadrangle map, 1:250,000-scale ID
Quadrangle map, 1:63,360-scale C-3
Latitude 62.6148
Longitude -157.1711
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Broken Shovel prospect is about 0.3 mile southeast of hill 2225 and 1.2 mile northwest of the Moore Creek placer mine (ID084). It is at an elevation of about 1,700 feet, about 0.3 mile southwest of the center of section 9, T. 29 N., R. 42 W., of the Seward Meridian. The location is accurate. Work in 2007 nearby identified nearby mineralization in the Spring and Troy Zones.

Geologic setting

Geologic description

The Broken Shovel prospect is a N20E-trending, steeply dipping quartz-dolomite-sulfide vein in medium-grained monzonite of the Upper Cretaceous, Moore Creek pluton (Bundtzen, Laird, and Lockwood, 1988; Miller, Bundtzen, and Gray, in press). The pluton has been dated at 68.9 Ma (Miller, Bundtzen, and Gray, 2005) The Broken Shovel vein, as defined in prospect trenches and rubble, is about 5 feet thick and can be traced along strike for about 650 feet. Both walls of the vein are sericitized and a pocket of tourmaline is exposed near the its southwest end (Bundtzen, Laird, and Lockwood, 1988). Grab and chip-channel samples contained up to 555 parts per million (ppm) silver, 1,600 parts per billion (ppb) gold, 4,860 ppm copper, 1,430 ppm lead, 760 ppm zinc, 5,500 ppm arsenic, and 2,400 ppm antimony (Bundtzen, Laird, and Lockwood, 1988; McGimsey and others, 1988). Arsenopyrite, scheelite, visible gold, and lead-antimony sulfosalts have been identified in both hand specimen and by microprobe analysis; gold and tungsten values may be understated in the chemical analyses of the samples.
The Broken Shovel prospect has been investigated intermittently since the 1930s by placer miners from Moore Creek, notably Elmer Keturi and Jules Stuver, who prospected the lode in the 1940s and 1950s (Don Harris, oral communication, 1983). When the prospect was examined in 1983 by the Alaska Division of Geological and Geophysical Surveys, it had been explored both by modern bulldozer cuts and much older hand-dug prospect pits (Bundtzen, Laird, and Lockwood, 1988).
On the basis of numerous chip-channel surface samples, Bundtzen, Laird, and Lockwood, (1988) estimated that the Broken Shovel prospect contains an inferred resource of about 16,000 tons of material that contained about 150.0 ppm silver, and about 1.0 percent combined base metals. The average gold grade was not determined.
In early 2008, Full Metals and Highbury Projects, Inc. were jointly exploring the area under a letter of agreement (Full Metal Minerals, 2008, Moore Creek; 2008, Trenching) . They dug numerous trenches and identified three zones with multiple types of mineralization. In the Spring Zone, sheeted quartz-tourmaline veins contain coarse gold and disseminated sulfides. Several notable samples across widths of from 4.0 to 11.0 meters contained 2.17 to 8.86 grams of gold per ton. The mineralization in the Troy Zone consists of gold-quartz veins in a wider zone of lower grade gold mineralization. Notable samples of the veins included 0.2 meters with 88.5 grams of gold per ton and 0.2 meters with 36.0 grams of gold per ton; these occur within a 3.0-meter-long channel sample that averaged 7.6 grams of gold per ton. The Broken Shovel zone is a steeply dipping quartz vein; twelve samples contained from a trace to 3.84 grams of gold per ton and 2.0 to 1,105 grams of silver per ton, along with anomalous bismuth, arsenic, and mercury.
Geologic map unit (-157.173460297121, 62.614121225892)
Mineral deposit model Gold-silver-quartz veins with sulfides.
Age of mineralization Unknown; the Moore Creek pluton that hosts some of the mineralization is 68.9 Ma (Bundtzen, Laird, and Lockwood, 1988).
Alteration of deposit The rocks adjacent to the vein have been altered to sericite, dolomite, and tourmaline.

Production and reserves

Workings or exploration The Broken Shovel prospect has been investigated intermittently since the 1930s by placer miners from Moore Creek, notably Elmer Keturi and Jules Stuver, who prospected the lode in the 1940s and 1950s (Don Harris, oral communication, 1983). When the prospect was examined in 1983 by the Alaska Division of Geological and Geophysical Surveys, it had been explored both by modern bulldozer cuts and by much older hand-dug prospect pits (Bundtzen, Laird, and Lockwood, 1988). The U.S. Geological Survey also investigated the prospect in 1985 (McGimsey and others, 1988). In early 2008, Full Metals and Highbury Projects, Inc. were jointly exploring the area under a letter of agreement (Full Metal Minerals, 2008, Moore Creek, 2008). They dug numerous trenches and identified three zones with multiple types of mineralization: the Spring, Troy, and Broken Shovel zones.
Indication of production None
Reserve estimates Based on numerous chip-channel surface samples, Bundtzen, Laird, and Lockwood, (1988) estimated that the Broken Shovel prospect contains an inferred resource of about 16,000 tons of material with about 150.0 ppm silver, and about 1.0 percent combined base metals. The average gold grade was not determined.

References

References

Reporters T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.), M.L. Miller (U.S. Geological Survey); and C.C. Hawley (Hawley Resource Group); D.J. Grybeck (Port Ludlow, WA)
Last report date 3/4/2008