Whistler

Prospect, Active

Commodities and mineralogy

Main commodities Ag; Au; Ba; Cu; Pb; Zn
Other commodities Fe
Ore minerals chalcopyrite; galena; gold; magnetite; pyrite; sphalerite
Gangue minerals carbonate; chlorite; gypsum; quartz

Geographic location

Quadrangle map, 1:250,000-scale TY
Quadrangle map, 1:63,360-scale D-8
Latitude 61.9638
Longitude -152.6799
Nearby scientific data Find additional scientific data near this location
Location and accuracy The center of the Whistler prospect is about 3.8 miles west of the junction of Portage Creek and the Skwentna River, near the center of section 29, T. 22 N., R. 18 W., of the Seward Meridian. The location is accurate to within 500 feet.

Geologic setting

Geologic description

In early 2010, the Whistler prospect was the most developed property of the Whistler project of Kiska Metals Corporation and was aggressively being explored (Kiska Metals Corporation, 2010). Cominco Alaska began mineral exploration in the area in 1986; they drilled 15 short holes on the Whistler prospect but dropped it in 1989. It was restaked in 1999 and leased to Kennecott Exploration Company in late 2002. From 2004 through 2006, Kennecott carried out major exploration in the area, including geologic mapping; soil, stream sediment, and rock geochemistry; ground induced-polarization and airborne magnetic geophysical surveys; and they drilled 15 core holes in the Whistler prospect that totaled 7,948 meters. In 2007, Geoinformatics Exploration Inc. optioned the property from Kennecott. As of 2008, the Whistler prospect is on a block of 732 State of Alaska mining claims (Wahl and others, 2008). In 2009, Kiska Metals Corporation, was formed through a merger of Geoinformatics and Rimfire Minerals Corporation (Morris, 2011).
The Whistler prospect is a porphyry copper-gold deposit that in 2010 extended over an area at least 1,000 meters in diameter (Kiska Metals Corporation, 2010; Wahl and others, 2008). It is closely associated with a [Cretaceous-]Tertiary extrusive igneous complex that overlays and intrudes feldspathic sandstone of Jurassic-Cretaceous age (Wilson and others, 2009). At least three diorite porphyry intrusive phases intrude the feldspathic sandstone unit and are associated with the sulfide mineralization event at Whistler, although strong phyllic alteration has obliterated primary textures, making it difficult to differentiate lithologies and determine intrusive contacts. The oldest intrusive phase (‘main stage’) exhibits the best gold-copper mineralization; the second oldest phase (‘inter-mineral stage’) is strongly altered and carries weak gold-copper mineralization, while the third and youngest is altered but typically barren. Most of the complex consists of 'inter-mineral stage' and 'main stage' diorite porphyry; the best mineralization is in the main-stage porphyry. The complex is cut by dikes of 'late stage' diorite porphyry and porphyritic andesite. The structure is not well constrained because of the wide spacing of the drill holes but there is at least one major fault and several breccia zones (Wahl and others, 2008). Roberts (2014) reported diorite porphyry bodies at the Whistler deposit occur as batholiths, stocks, and dikes and generally have a northwest-oriented elongation that is sub-parallel to significant regional-scale faults, such as the Alger Peak fault and the Timber Creek fault.
The paragenesis of the mineralization is: 1) early barren, quartz-magnetite veins associated with secondary biotite alteration; 2) 'main' stage, quartz-magnetite-chalcopyrite veins, associated with secondary biotite, quartz-pyrite and pyrite veins, and pervasive quartz-sericite-pyrite alteration, and 3) late calcite veins with sphalerite and galena. Gypsum is common. Near the complex, the original textures of the sedimentary rocks are almost obliterated by strong phyllitic alteration that makes it hard to distinguish them from the igneous rocks (Wahl and others, 2008).
In January of 2011, Kiska announced a new estimate of the resources of the Whistler deposit that incorporated the drilling through 2010 (Kiska Metals Corporation, 2011; Morris, 2011). They estimate it has 79.2 million tonnes of 'indicated resource' with a grade of 0.51 gram of gold per tonne, 1.97 grams of silver per tonne, and 0.17 percent copper, and an 'inferred resource' of 145.8 million tonnes with an average grade of 0.40 gram of gold per tonne, 1.75 grams of silver per tonne, and 0.15 percent copper (Morris, 2011).
Geologic map unit (-152.682134680801, 61.9632175119588)
Mineral deposit model Gold-copper porphyry (Cox and Singer, 1986; model 20c)
Mineral deposit model number 20c
Age of mineralization Younger than or related to a Cretaceous-Tertiary diorite porphyry, intrusive-extrusive complex (Morris, 2011).
Alteration of deposit Early secondary biotite alteration in the porphyry; intense quartz-sericite-pyrite alteration during the main stage of mineralization in the porphyry; and strong phyllitic alteration in the sandstone around the intrusion (Wahl and others, 2008).

Production and reserves

Workings or exploration
In early 2010, the Whistler prospect was the most developed property of the Whistler project of Kiska Metals Corporation and was aggressively being explored (Kiska Metals Corporation, 2010). Cominco Alaska began mineral exploration in the area in 1986; they drilled 16 diamond drillholes (1,677 meters) and completed 8.4 line-kilometers of 2D Induced Polarization (IP) geophysics for the Whistler deposit, but dropped it in 1989 (Morris, 2011). It was restaked in 1999 and leased to Kennecott Exploration Company in late 2002. From 2004 through 2006, Kennecott carried out major exploration in the area, including geologic mapping; soil, stream sediment, and rock geochemistry; ground induced-polarization and airborne magnetic geophysical surveys; and they drilled 15 core holes in the Whistler prospect that totaled 7,948 meters. In 2007, Geoinformatics Exploration Inc. optioned the property from Kennecott. As of 2008, the Whistler prospect is on a block of 732 State of Alaska mining claims (Wahl and others, 2008). From 2007 through 2008, Geoinformatics drilled 12 holes for 5,784 meters in order to infill the Whistler deposit to sections spaced at 75 meters and to test for the extent of the deposit to the north and south (Morris, 2011).
Results from airborne magnetic surveys (using 50-meter spacing) by Kennecott in 2004 showed that the Whistler deposit displays a strong 900 meter by 700 meter positive magnetic anomaly attributed to the Whistler Diorite intrusive complex, secondary magnetite alteration and veining associated with gold-copper mineralization. Additionally, two IP lines run over the deposit magnetic anomaly showed that mineralization is coincident with a strong chargeability anomaly. Soil grids over the deposit showed anomalous gold-copper results that were also coincident with the magnetic high (Morris, 2011).
In 2009, Kiska Metals Corporation, was formed through a merger of Geoinformatics and Rimfire Minerals Corporation. In 2010, Kiska drilled 5 holes in the Whistler deposit totaling 4,456 meters in order to infill gaps from previous drilling and to test the edges and depth of the intrusive complex that hosts the deposit (Morris, 2011). In 2011, Kiska performed minor infill drilling at the Whistler Deposit, followed by publication of an updated 43-101 compliant resource estimate (Roberts, 2014).
Indication of production None
Reserve estimates
In 2011, Kiska announced a new estimate of the resources of the Whistler deposit that incorporated the drilling through 2010 (Morris, 2011). The pit delineated resource has 79.2 million tonnes of 'indicated resource' with a grade of 0.51 gram of gold per tonne, 1.97 grams of silver per tonne, and 0.17 percent copper, and an 'inferred resource' of 145.8 million tonnes with an average grade of 0.40 gram of gold per tonne, 1.75 grams of silver per tonne, and 0.15 percent copper (Morris, 2011).
In 2016, Brazil Resources Inc. (now Gold Mining Inc.) is evaluating prospects it acquired from Kiska Metals Corporation in 2015. Although no on-site work was performed in 2016 at the Whistler, Raintree West (TY038), and Island Mountain (TY018) porphyry copper–gold–silver prospects, in May of 2016, Brazil Resources Inc. released a new technical report announcing the first resource estimates for the Raintree West (TY038) and Island Mountain (TY018) deposits, largely based on drilling by Kiska Metals Corporation between 2009 and 2011 (Giroux, 2016). Their report also re-states the resource estimate for the Whistler gold-copper deposit (initially released in 2015), based largely on the historic resource estimate completed by Kiska Metals Corporation in March 2011 (Athey and Werdon, 2017).
The Whistler deposit contains an indicated resource of 79.2 million tonnes, averaging 0.51 gram of gold per tonne (1.28 million ounces of gold), 1.97 grams of silver per tonne (5.03 million ounces of silver), and 0.17 percent copper (302 million pounds of copper). Additionally, Whistler contains an inferred resource of 145.8 million tonnes grading 0.40 gram of gold per tonne (1.85 million ounces gold), 1.75 grams of silver per tonne (8.21 million ounces silver), and 0.15 percent copper (467 million pounds copper). Metal recoveries reported for the Whistler deposit resource estimate include 85 percent for copper, 75 percent for gold, and 75 percent for silver (Giroux, 2016).

References

MRDS Number A106263

References

Kiska Metals Corporation, 2010, Whistler project overview; http://www.kiskametals.com/s/Whistler.asp?ReportID=370036 (as of February 26, 2010).
Kiska Metals Corporation, 2011, Kiska published revised Whistler resource estimate and provides further details for 2011 program, Whistler project, Alaska: http://www.kiskametals.com/s/News.asp?ReportID=437453 (News release, January 12, 2011).
Morris, R.J., 2011, Resource Estimate Update for the Whistler Gold Copper Deposit and Results of Property Wide Exploration, Yentna Mining District, Alaska: Technical Report (43-101) for Kiska Metals Corporation, 133 p. (posted on www.sedar.com, March 18, 2011) http://www.sedar.com/GetFile.do?lang=EN&docClass=24&issuerNo=00007774&fileName=/csfsprod/data115/filings/01703222/00000003/i%3A%5CSEDAR%5CKMTchRpAM.PDF (as of January 8, 2015).
Roberts, Michael, 2014, Whistler Project Executive Summary Report, Kiska Metals Corporation: http://www.kiskametals.com/i/pdf/Kiska_Whistler_ExecutiveSummary_24Jan2014.pdf (as of March 10, 2014).
Wahl, George, Coutture, Jean-Francois, and Keller, G.D., 2008, Mineral resource estimation, Whistler copper-gold project, Alaska Range, Alaska: Technical report for Geoinformatics Exploration, Inc., 124 p. (posted on www.sedar.com, February 22, 2008) http://www.sedar.com/GetFile.do?lang=EN&docClass=24&issuerNo=00007774&fileName=/csfsprod/data86/filings/01219440/00000001/s%3A%5Cgxl222.pdf (as of January 8, 2015).
Reporters Madelyn A. Millholland (Anchorage); D.J. Grybeck (Contractor, USGS); V.C. Zinno (Alaska Earth Sciences, Inc.); M.B. Werdon (DGGS)
Last report date 8/26/2017