Stumble-on

Prospect, Active

Alternative names

Mammoth
Cayenne

Commodities and mineralogy

Main commodities Ag; Au; Cu; Zn
Ore minerals chalcopyrite; copper; gahnite; magnetite; pyrite; pyrrhotite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale CR
Quadrangle map, 1:63,360-scale B-2
Latitude 55.29674
Longitude -132.37202
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Stumble-on prospect is at an elevation of about 1,300 feet, 0.8 mile east-southeast of the mine symbol for the Khayyam Mine on the USGS, 1:63,360 scale topographic map. (The Khayyam Mine is not at the symbol; see CR129 for its actual location.) The Stumble-on prospect is about 0.2 mile north-northeast of the center of section 8, T. 76 S., R. 86 E. The location is accurate.

Geologic setting

Geologic description

The deposit at the Stumble-on Mine was discovered in about 1899, probably at the same time as the nearby Khayyam Mine (CR129) (Brooks, 1902; Wright and Wright, 1908; Fosse, 1946; Bufvers, 1967; Barrie, 1984; Barrie and Kyle, 1988; Roppel, 1991; Maas and others, 1995). The Stumble-on, first called the Mammoth, was developed by 2 adits with about 530 feet of workings, an open cut, and several trenches. There is no record of production.
In 2007, The Niblack Mining Corp. acquired the Stumble-on prospect and the Khayyam Mine (CR129) and they are being explored together as the Cayenne property (Niblack Mining Corp., 2008) In 2007, Niblack carried out geologic mapping, collected rock samples, and did a geophysical ground, resistivity survey along 2.5 kilometers of line. Their Cayenne samples (at the Khayyam Mine?) included a 2-meter chip sample of massive sulfides that contained 0.88 percent copper, 9.66 percent zinc, 6.2 grams of silver per tonne, and 0.30 gram of gold per tonne. Several large boulders from the mine dump contained up to 14.6 percent zinc, 15.4 percent copper, 109 grams of silver per tonne, and 5.72 grams of gold per tonne.
Detailed mapping (Barrie, 1984; Barrie and Kyle, 1988) indicates that the deposit at the Stumble-on prospect is a stratiform, massive-sulfide lens in Late Proterozoic or Cambrian metamorphic rocks of the Wales Group. The host rocks consist mainly of schist of volcanic origin. The main units are (hornblende-quartz-)chlorite-plagioclase schist and (chlorite-)hornblende-plagioclase schist. The rocks consistently strike about N75W and dip steeply to the north and south. Minor amounts of garnet, sericite, stilpnomelane, and epidote also occur in the schist. Recent detailed geochemical and isotopic work by Slack and others (2002) confirm that the deposit is of late Proterozoic or Cambrian age.
The deposit at the Stumble-on prospect consists of a single, massive-sulfide lens about 6 feet thick that is exposed for about 560 feet (Barrie, 1984; Barrie and Kyle, 1984; Maas and others, 1995). The lens consists mainly of pyrite with subordinate chalcopyrite, pyrrhotite, and magnetite. A ground geophysical survey (VLF-EM) indicates that the body continues to the east under surficial material. The deposit is essentially the same as the one at the nearby Khayyam Mine (CR129), and much of the geologic and exploration work there probably extends to the area of the Stumble-on prospect. Bedrock between the two deposits is largely covered by surficial material, but they may be on the same stratigraphic horizon. The Stumble-on prospect has been sampled many times with similar results that vary mostly by the sample selection. Maas and others (1995), for example, sampled extensively. Their best samples contained 5.96 percent copper, 3.61 percent zinc, 43.7 parts per million (ppm) silver, and 3.916 ppm gold; the average value of their 24 samples was 0.92 percent copper, 0.20 percent zinc, 691 ppm silver, and 1.12 ppm gold.
Geologic map unit (-132.373699260378, 55.2963807733498)
Mineral deposit model Besshi massive-sulfide deposit (Cox and Singer, 1986; model 24b).
Mineral deposit model number 24b
Age of mineralization Volcanogenic, massive sulfide deposit in late Proterozoic or Cambrian metamorphic rocks.
Alteration of deposit Probably similar to that at the Khayyam Mine (CR129).

Production and reserves

Workings or exploration The Stumble-on prospect was developed by 2 adits with about 530 feet of workings, an open cut, and several trenches. Banner Mining Company drilled 14 holes in 1971 at the Khayyam Mine (CR129) and 11 holes at the Mammoth (Stumble-On) prospect. Cominco Exploration mapped and sampled the property in 1972 and 1973. Homestake Mining Company examined the property in 1975 (Hite, 1976). The deposit was sampled by the U.S. Bureau of Mines (Maas and others, 1995). In 2007, The Niblack Mining Corp. acquired the Stumble-on prospect and the Khayyam Mine (CR129) and they are being explored together as the Cayenne property (Niblack Mining Corp., 2008). In 2007, Niblack carried out geologic mapping, collected rock samples, and did a geophysical ground, resistivity survey along 2.5 kilometers of line.
Indication of production None
Production notes There is no record of production.

References

MRDS Number A010059

References

Barrie, C.P., 1984, The geology of the Khayyam and Stumble-On deposits, Prince of Wales Island, Alaska: University of Texas at Austin, M.A. thesis, 171 p.
Hite, J.B., 1976, Khayyam project, Prince of Wales Island, Alaska: Homestake Mining Company, 4 p. and maps. (Unpublished reports held as files 6810.2, 6811.03, and 681.04, Anaconda Collection, American Heritage Center, University of Wyoming, Laramie.)
Niblack Mining Corporation, 2008, Cayenna, introduction: http://www.niblackmining.com/s/Cayenne.asp (as of May 5, 2008).
Roppel, Patricia, 1991, Fortunes from the earth: Manhattan, Kansas, Sunflower University Press, 139 p.
Slack, J.F., Shanks, W.C. III, Karl, S.M., Ridley, W.I., and Bittenbender, P.E., 2002, Geochemical and sulfur isotope compositions of Late Proterezoic and early Paleozoic volcanogenic massive sulfide deposits, Prince of Wales Island and vicinity, southeastern Alaska (abs.): Geological Society of America, Abstracts with Programs, v. 34 (6), p. 113.
Reporters D.J. Grybeck (Port Ludlow, WA)
Last report date 6/5/2008