Saddle Mountain

Prospect, Active

Commodities and mineralogy

Main commodities Au
Other commodities Cu
Ore minerals chalcopyrite; gold; magnetite; pyrite
Gangue minerals calcite; chalcedony; chlorite; quartz

Geographic location

Quadrangle map, 1:250,000-scale RM
Quadrangle map, 1:63,360-scale A-3
Latitude 61.0972
Longitude -159.7768
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Saddle prospect is at an elevation of about 2,440 feet on the crest of a ridge east of upper Bonanza Creek. It is about 0.5 mile south-southwest of hill 2765 and about 0.3 mile east-southeast of the center of section 29, T. 12 N., R. 59 W., of the Seward Meridian. The location is probably accurate to within 1,000 feet.

Geologic setting

Geologic description

Frost (1990) describes gold- and pyrite-bearing quartz veins cutting sericitized andesite and volcaniclastic hornfels at this site. The veins are vuggy and contain euhedral quartz prisms extending into open spaces. The other common gangue minerals in the iron-oxide stained veins are calcite and chlorite. A quartz vein at this prospect contained 20 parts per million (ppm) gold (Frost, 1990, sample locality 2). The rocks in the area include thermally metamorphosed Jurassic volcanic or volcaniclastic rocks near the contact with a small granitic stock (Box and others, 1993). The thermal metamorphism is caused by a large mid-Cretaceous granitic pluton exposed to the the north in the headwaters of the Tuluksak River.
Wenz (2004, 2005) describes both high and low temperature mineralization at this prospect. Quartz-chlorite-calcite veins with magnetite, chalcopyrite, and native gold are part of the higher temperature suite. Fluid inclusions in these veins have first homogenization temperatures of 282 to 557 degrees centigrade and salinities of 17 to 57 weight percent NaCl. Samples of this mineralization contain up to 10.9 ppm gold. The lower temperature mineralization includes vuggy chalcedony-bearing veins that are known to contain up to 723 parts per billion (ppb) gold, 9.88 ppm silver, and 280 ppb mercury. Sericite-altered dikes and carbonate-replaced fault breccia are also considered part of the lower temperature mineralization. Altered fault breccia contains up to 15.1 ppm gold and 1.6 ppm mercury.
In 2005, Tonogold Resources, Inc. (2006) negotiated a mining lease agreement with Calista Corporation covering the Nyac area. They completed detailed soil geochemical surveys in several areas including this prospect in the summer of 2005. Strachan (2005) shows a map of soil samples in the area of this prospect. He reported that 58 of 518 surface samples contained 0.105 to 2.86 ppm gold. Seven rock chip samples contained 0.121 to 15.1 ppm gold.
In 2006, Tonogold (2007) expanded their geochemical coverage of the area considerably, did surface mapping and sampling, and cut several trenches. Some outcrop and float samples which had visible gold contained more than 1,000 ppm gold. Wenz (2004, 2005) also maps a large area of gaudy, orange-weathering altered volcanic rocks with anomalous gold values in the flat saddle between this prospect and hill 2046 to the southeast and on the hillside between that saddle and this prospect.
In 2010, Nyac Mining LLC, drilled several hole near the Saddle prospect (Flanders, 2010). The holes penetrated 1,500 feet of intensely quartz-sericite-pyrite-magnetite-gypsum-anhydrite-biotite altered Jurassic andesite with large intervals of hydrothermal breccia and some porphyry and granite dikes Some notable intercepts were 18 feet with 1.88 grams of gold per tonne, 3.7 feet with 5.89 grams of gold per ton, and 24.9 feet with 1.21 grams of gold per ton. Flanders suggest that the rocks overlay a buried intrusive that is the source of the gold.
In 2011, Nyac Gold LLC performed prospecting and diamond drilling at Saddle Mountain to test a mineralized breccia pipe with deep holes. Reconnaissance mapping was conducted, in addition to magnetic susceptibility readings at outcrops and talus exposures (Flanders and others, 2011).
In 2012, Nyac Gold LLC completed prospecting activities, reconnaissance mapping, in addition to diamond drilling at Saddle Mountain to test a mineralized breccia pipe with deep holes (Flanders and others, 2012).
In 2013, Nyac Gold LLC completed prospecting activities and seven diamond drill holes totaling 8,248 feet. Major oxide and trace element analyses were conducted on plutonic rocks but the results were not available as of the revision date of this report (Flanders, 2013).
Geologic map unit (-159.77910564918, 61.0964698106489)
Mineral deposit model Gold-quartz veins over a possible intrusion-related-gold deposit.
Age of mineralization Wenz (2004) reports Ar-Ar ages of 113 +/- 1 Ma of intrusive rocks near this prospect.
Alteration of deposit Silicification, sericitization, and carbonate replacement (Wenz 2004, 2005).

Production and reserves

Workings or exploration
In 2005, Tonogold Resources, Inc. (2006) negotiated a mining lease agreement with Calista Corporation covering the Nyac area. They completed detailed soil geochemical surveys in several areas including this prospect in the summer of 2005. In 2006, they markedly expanded the soil survey around this prospect, mapped the surface in the vicinity, and cut several trenches. In 2010, Nyac Mining LLC, drilled several hole near the Saddle prospect (Flanders, 2010).
In 2011, Nyac Gold LLC performed prospecting and diamond drilling at Saddle Mountain to test a mineralized breccia pipe with deep holes. Reconnaissance mapping was conducted, in addition to magnetic susceptibility readings at outcrops and talus exposures (Flanders and others, 2011).
In 2012, Nyac Gold LLC completed prospecting activities, reconnaissance mapping, in addition to diamond drilling at Saddle Mountain to test a mineralized breccia pipe with deep holes (Flanders and others, 2012).
In 2013, Nyac Gold LLC completed prospecting activities and seven diamond drill holes totaling 8,248 feet. Major oxide and trace element analyses were conducted on plutonic rocks but the results were not available as of the revision date of this report (Flanders, 2013).
Indication of production None
Reserve estimates None.
Production notes None.

References

References

Flanders, Richard, 2013, 2013 Drilling and Exploration for Lode Gold Deposits in the Nyac District, Southwest Alaska, 36 p.(Report held by Calista Corporation, Anchorage, Alaska).
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).
Flanders, Richard, Van der Poel, W.I., Deininger, James, 2012, 2012 Drilling and Exploration for Lode Gold Deposits in the Nyac District, Southwest Alaska, 25 p. (Report held by Calista Corporation, Anchorage, Alaska).
Strachan, D. G., 2005, A summary and interim status report on Tonogold's 2005 geochemical exploration of the Nyac gold district, southwest Alaska: Private report for Tonogold Resources, 20 p. (Available online at: http://www.tonogold.com/in/pdf/2005_Final_Report_5m[1].pdf).
Tonogold Resources, Inc., 2006: www.tonogold.com/s/Nyac.asp (as of April, 2007).
Tonogold Resources, Inc., 2007: www.tonogold.com/s/Nyac.asp (as of April, 2007).
Wenz, Z. J., 2004, Geology and gold mineralization of the Nyac district, southwest Alaska: MS thesis, University of Alaska, Fairbanks, 133 p.
Reporters Travis L. Hudson (Applied Geology, Inc.); D.J. Grybeck (Contractor, USGS); V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 12/20/2014