Goodrich Porphyry

Prospect, Active

Commodities and mineralogy

Main commodities Au; Cu; Mo
Other commodities Ag; As; Ba; Bi; Mn; Pb; Sb; W; Zn
Ore minerals arsenopyrite; bismuthite; boulangerite; chalcopyrite; galena; gold; pyrite; sphalerite
Gangue minerals barium; quartz

Geographic location

Quadrangle map, 1:250,000-scale TC
Quadrangle map, 1:63,360-scale A-1
Latitude 63.0569
Longitude -141.091
Nearby scientific data Find additional scientific data near this location
Location and accuracy Goodrich Porphyry is a prospect located 3.7 miles east of VABM 3385 'Flat', 0.4 mile north from the center of section 29, T. 15 N., R. 23 E., of the Copper River Meridian This location is accurate to within 500 feet of the center of the prospect.

Geologic setting

Geologic description

Goodrich Porphyry is part of the Blue Moose Exploration, Inc. (BME) project located in the Moosehorn Range on the Alaska-Yukon border. The Moosehorn Range is located in the Tintina Gold Belt, in the Dawson Range Batholith of the Yukon-Tanana Terrane (Joyce, 2002). The BME project geology consists of regional gneiss and schist intruded by a Mid-Cretaceous granodiorite and a quartz-rich mineralized porphyry. The area is unglaciated, and Moosehorn Range outcrop exposures are limited (Handverger, 2015).
The principal Moosehorn host rock is hornblende-biotite granodiorite. The mineralogy is 20 to 30 percent quartz, 25 to 45 percent plagioclase, 10 to 20 percent potassium-feldspar, 10 to 15 percent biotite, 10 percent hornblende, and titanite, pyrite, magnetite, allanite, epidote, and chlorite. The hornblende may be altered to biotite +/- sericite and chlorite. Feldspars may be sericitized (Joyce, 2002).
Using geochemical sampling, BME discovered and staked the Goodrich Porphyry, a quartz-rich mineralized intrusive underlying almost two square miles. Soil and rock geochemistry, trench sampling and mapping and 31 short (under 22 feet) churn drill holes have established anomalous values of gold, silver, arsenic, copper, molybdenum, antimony, strongly anomalous barium, zinc and manganese (Handverger, 2015).
The geology from a 4,600 foot-long trench excavated by BME in 2001 consists predominantly of altered quartz-rich rocks including quartz (+/-feldspar) porphyries and totally silicified units. Unaltered Moosehorn granodiorite and small intermediate dikes make up less than ten percent of the rocks exposed in the trench. Some of the silicic units indicate total quartz flooding showing ghosts of former feldspar crystals . Intense fracturing followed by silica invasion was observed. Limonitic veinlets with gossan boxworks after sulfides were identified and one tiny specimen of chalcopyrite was identified. A quartz-eye unit hosted limonitic veinlets and locally intense fracturing approaching a breccia (Handverger, 2015).
The 2014 pit sampling program of bedrock of the Goodrich Porphyry established evidence of a highly fractured, altered, supergene, leached capping of a mineralized copper porphyry system (Handverger, 2015).
Geologic map unit (, )
Mineral deposit model Porphyry Cu-Mo (Cox and Singer, 1986; model 21a).
Mineral deposit model number 21a
Alteration of deposit Quartz-flooding of quartz-feldspar porphyries (Handverger, 2015).

Production and reserves

Workings or exploration
The initial discovery of gold in the Moosehorn Range occurred in 1970 during a Quintana Minerals Corp. porphyry copper exploration program. The first placer gold claims were staked shortly after, and the Moosehorn Range has been the site of placer operations since then. The placer and limited hard rock mining production in the Moosehorn Range exceeds 100,000 ounces of gold (Handverger, 2015), largely in Canada.
In 1975, Great Bear Mining Ltd. conducted the first significant gold exploration project in the Canadian portion of the Moosehorn Range. In 1990, Canada Tungsten conducted a placer gold exploration program on the Alaskan side of the border (Handverger, 2015).
Blue Moose Exploration, Inc. (BME) first staked claims on the Alaska side of the Moosehorn Range in 1993. In 1999, BME conducted a widespread soil geochemical survey program of 111 samples in Alaska along the west side of the Moosehorn Range. This was followed up in 2000 by a 420-sample program over fifteen square miles in the same area. In 2010, Millrock Resources staked claims around the BME property and conducted an additional 252 soil sampling geochemical program on and around BME claims (Handverger, 2015).
In 2001, following up on anomalous soil geochemical results, BME personnel excavated a 4,600 foot-long trench cross-cutting the Goodrich Porphyry. Forty-five rock samples were collected and assayed from this trench. The highest trench rock sample contained 0.021ppm gold, 6.4 ppm silver, 540 ppm copper, 616 ppm molybdenum, 3677 ppm lead, 693 ppm zinc, 213 ppm antimony, 54 ppm bismuth, and 2.59 ppm mercury (Handverger, 2015).
During the summer field season of 2011, Blue Moose completed 33 shallow drill holes on the Goodrich Porphyry target to sample the bedrock below the frozen soil horizons. A total of 416 holes were drilled using a down-hole hammer with a 4.5-inch bit. The depth of the holes ranged from 4.0 to 22.5 feet with a median depth of 12.5 feet; 128 samples were assayed. The dimensions of the area drilled are 8,000 feet by 2,000 feet (Handverger, 2015).
The 2014 pit sampling program of bedrock on the Goodrich Porphyry established evidence of a highly fractured, altered, supergene, leached capping of a mineralized copper porphyry system (Handverger, 2015).
Indication of production None

References

References

Reporters V.C. Zinno (Alaska Earth Sciences, Inc.); N.V. King (Alaska Earth Sciences, Inc.)
Last report date 3/15/2016