Prospect, Active

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Zn
Ore minerals chalcopyrite; galena; gold; sphalerite
Gangue minerals carbonates; quartz

Geographic location

Quadrangle map, 1:250,000-scale TY
Quadrangle map, 1:63,360-scale D-7
Latitude 61.9557
Longitude -152.6082
Nearby scientific data Find additional scientific data near this location
Location and accuracy The center of the Rainmaker prospect is about 1.6 miles southwest of the mouth of Portage Creek on the Skwentna River and about 0.3 mile northeast of the center of section 32, T. 22 N., R. 18 W., of the Seward Meridian. The location is accurate to within 500 feet.

Geologic setting

Geologic description

The Rainmaker prospect is situated in a Cretaceous to Tertiary continental margin arc. It is underlain by flysch sediments of the Kahiltna assemblage and is one of several gold-copper porphyry deposits that form a belt that trends north-northwest for at least 9 miles (Wahl and others, 2008; Kiska Metals Corporation, 2010). The best known is the Whistler deposit (TY022), about 3 kilometers to the west-northwest of Rainmaker. As of early 2010, relatively little detail is available on the Rainmaker prospect; it is largely covered by surficial material, but it is probably similar to the Whistler deposit.
The Rainmaker prospect occurs in a low-lying, glacial-till covered valley floor (Morris, 2011). Rainmaker is hosted by diorite porphyry dikes cutting porphyritic andesite centers within a volcanic basin. A large, semi-circular induced polarity (IP) chargeability high anomaly at Rainmaker has been confirmed by mapping and drilling to be related to extensive phyllic alteration of quartz-sericite-pyrite indicative of porphyry potential. An intense circular aeromagnetic high also exists (Roberts, 2014).
The style of alteration, mineralization, veining and cross-cutting relationships displayed is generally typical of porphyry systems associated with relatively oxidized magma series (quartz vein stockwork, chalcopyrite-pyrite ore assemblage, presence of sulfates, and core of potassic alteration with well-developed peripheral phyllic alteration zones). Mineralization occurs at bedrock surfaces immediately below till cover (Roberts, 2014).
Geologic map unit (-152.610431194648, 61.9551196947664)
Mineral deposit model Gold-copper porphyry (Cox and Singer, 1986; model 20c)
Mineral deposit model number 20c
Age of mineralization Paleocene to Late Cretaceous based on age of host diorite, monzonite and granite (Roberts, 2014).
Alteration of deposit Typical of porphyry systems associated with relatively oxidized magma series (quartz vein stockwork, chalcopyrite-pyrite ore assemblage, presence of sulfates, core of potassic alteration with well-developed peripheral phyllic alteration zones) (Morris, 2011).

Production and reserves

Workings or exploration
The prospect is at the southern end of a belt of porphyry gold-copper mineralization that has been extensively explored by several companies since the early 1980s.
Cominco Alaska began mineral exploration in the area in 1986 but they ended their work in 1989. From 2004 to 2006, Kennecott Exploration Company was active in the area and staked several large blocks of claims that included the Raintree prospect. Geoinformatics Exploration Inc. acquired the property from Kennecott (Wahl and others, 2008). In 2009, Kiska Metals Corporation, the current (2010) holder of the claims, was formed by a merger of Geoinformatics and Rimfire Minerals Corporation (Morris, 2011).
Rainmaker was discovered during the 2004 to 2006 exploration period by Kennecott Exploration Company. In that time, Kennecott conducted extensive exploration of the region, including geological, geochemical, and ground induced polarization surveys, and drilling (Roberts, 2014).
There were at least 7 holes drilled on the Raintree prospect by 2008. In 2008, Geoinformatics drilled at least one hole on Raintree. A 184-meter intercept contained 0.44 grams of gold per tonne and 0.16 percent copper (Wahl and others, 2008).
Since 2010, it was being actively explored by Kiska Metals Corporation. Kiska’s work has included detailed mapping, geochemical and geophysical surveys, sampling, and at least seven drill holes between 2008 and 2011. Significant drilling intercepts include hole 05-DD-WH-REC-08, which returned 168.5 meters of 0.47 gram of gold per tonne, 2.25 grams of silver per tonne, 0.17 percent copper. As of 2014, drilling suggests that this prospect resembles approximately 100 meters diameter, steeply-dipping ‘pencil’-shaped porphyries (Roberts, 2014).
Five drill holes were drilled in 2011 by Kiska. Hole WH11-049 returned 104.4 meters that averaged 0.59 gram of gold per tonne and 0.20 percent copper (1.04 grams of gold per tonne equivalent) indicating improving grades with depth. Hole WH11-047 was successful in extending the Rainmaker zone 110 meters to the southeast, returning 58 meters of 0.35 gram of gold per tonne and 0.14 percent copper (0.69 gram of gold per tonne equivalent). Three holes stepping-out 350 meters to the southeast (holes WH11-043 and WH11-045) and 150 meters to the northwest (hole WH11-051) tested geophysical anomalies and shallow grid-drilling results and intersected strongly altered volcanic rocks with anomalous gold and copper values and local high grade silver-lead-zinc values (WH11-043: 34 meters averaging 44 grams of silver per tonne, 0.35 percent zinc, 0.27 percent lead) that may indicate stronger gold-copper porphyry mineralization in the vicinity (Kiska Metals Corporation, 2011).
Indication of production None
Reserve estimates None.
Production notes None.

Additional comments

The Whistler Deposit (TY022), which is within 3 kilometers of the Rainmaker prospect, has an existing 43-101 compliant resource: 2.25 million ounces of gold equivalent (Indicated category) and 3.35 million ounces of gold equivalent (Inferred category) (Morris, 2011).



Geoinformatics Exploration Inc., 2008, Geoinformatics provides update on regional targeting at Whistler project: http://www.kiskametals.com/i/pdf/2008-02-29_NR.pdf (News release, Feb. 29, 2008).
Kiska Metals Corporation, 2010, Whistler project overview; http://www.kiskametals.com/s/Whistler.asp?ReportID=370036 (as of Feb. 26, 2010).
Kiska Metals Corporation, 2011, Kiska Releases 2011 Drilling Results from the Whistler Orbit area, Whistler Projects, Alaska: (News release, Nov. 29, 2011) http://www.kiskametals.com/s/News.asp?ReportID=493101 (as of Jan. 12, 2015).
Kiska Metals Corportation, 2014, Whistler project overview; http://www.kiskametals.com/s/Whistler.asp?ReportID=370036 (as of March 10, 2014).
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 Jan. 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 Jan. 8, 2015).
Reporters D.J. Grybeck (Contractor, U.S. Geological Survey); V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 1/12/2015