RW Zone Prospect, Haines, Alaska, USAi

Regional Level Types
RW Zone Prospect	Prospect
Haines	City Borough
Alaska	State
USA	Country

Location: The prospect is approximately 3.0 miles, N58E from the summit of Mt. Henry Clay in the SE1/4, section 33, T. 2 S., R. 53 E. of the Copper River Meridian. Its location is taken from 1999 press releases of Rubicon Minerals (http://www.rubiconminerals.com) where the RW Zone is described as being located 1,600 feet from the Main Zone (SK066) between the Little Jarvis and Main Zone (SK066) showings. Still and others (1991) use the name 'Little Jarvis' for mineral showings on both the east and west sides of the Little Jarvis Glacier and this can be confusing. From Rubicon's press releases, it appears that the 'Little Jarvis' of Still and others (1991) on the east side of the Little Jarvis Glacier is only about 600 feet from Rubicon's RW Zone. Due to their apparent proximity, they are considered here as a single prospect.
Geology: Exploration by Rubicon Minerals in 1998 and drilling in 1999 discovered massive sulfide mineralization at the RW Zone. The RW Zone prospect is near the center of a 5-mile-long northwester trend that extends from the unnamed occurrences (SK070) at the northwest end through this prospect (SK067) and the Main Zone/Palmer prospect (SK066) to the Red Creek prospect (SK063) at the southeast end. Rubicon interprets the trend to represent the apex of a shallowly plunging, northwest-trending antiform. Mineralization intercepted in drill holes occurs both as: 1) chalcopyrite-sphalerite massive-sulfide mineralization, and 2) chalcopyrite-bearing, stringer-zone mineralization within a zone of strong chloritic alteration. The massive-sulfide, drill-intercept thicknesses range from 7.2 feet to 15 feet and contain up to 13.48% zinc, 1.89% copper, 2.98 ounces of silver per ton, and 0.02 ounces of gold per ton. Massive-sulfide drill intercepts extend over a dip length of 420 feet. The stringer-zone mineralization is beneath the massive sulfide horizon. One drill hole intercepted 156 feet of stringer-zone mineralization that included a 67.8-foot-thick interval with an average grade of 0.62% copper. Within the 67.8-foot-thick interval, there was a 16.2-foot interval that contained 1.50% copper. Surface samples from the nearby Little Jarvis prospect contain up to 13% zinc, 7% copper, and 7.0 ounces of silver per ton over a width of 15 feet. Rhyolites have been reported from the drill core. (Information summarized from Rubicon Minerals, 1998 and 1999). If the RW Zone and other similar prospects in the Mt. Henry Clay area are correlative with the Windy Craggy deposit in Canada and the Greens Creek deposit on Admiralty Island, then they are Late Triassic (Still, 1984 [OF 118-84]; Newberry and others, 1997).
Workings: At least 6 holes were drilled on the prospect in 1999 by Rubicon Minerals. This was the first drilling in the Porcupine Creek - Mount Henry Clay area to intersect ore-grade thicknesses of massive-sulfide mineralization (Rubicon Minerals, 1999).
Age: The RW Zone and other similar prospects in the Mt. Henry Clay area are probably correlative with the Windy Craggy deposit in Canada and the Greens Creek deposit on Admiralty Island and are therefore Late Triassic (Still, 1984 (OFR 118-84); Newberry and others, 1997).
Alteration: Sericitic, chloritic. The stringer zone below the massive sulfide horizon is chloritically altered.

Commodities (Major) - Ag, Cu, Zn; (Minor) - Au
Development Status: None
Deposit Model: Kuroko- or Besshi-type volcanogenic massive-sulfide deposit (Cox and Singer, 19

Other Databases

Link to USGS - Alaska:	SK067

Other Regions, Features and Areas containing this locality

References