Casey Glacier Sphalerite Occurrence, Hyder Mining District, Prince of Wales-Hyder Census Area, Alaska, USAi

Regional Level Types
Casey Glacier Sphalerite Occurrence	Occurrence
Hyder Mining District	Mining District
Prince of Wales-Hyder Census Area	Census Area
Alaska	State
USA	Country

Although no outcrop of the banded sulfides was found, the location of the boulder rubblecrop suggests that their source is beneath the icefield at the summit between Ferguson and Casey Glaciers (Maas, 1995, p. 235).
Location: The Casey Glacier Sphalerite occurrence consists of mineralized boulders of float scattered in an area of about a quarter of a square mile (Maas, 1995, p. 233, 235). The occurrence is in the northeast corner of Section 23 between elevations of about 3500 and 4100 feet, on a north-facing mountainside south of the West Fork of Texas Creek. It is about 2.0 miles east of Texas Lake. The above coordinates are for the approximate center of the area of float boulders. The location is accurate to within about a quarter of a mile.
Geology: The country rocks in the area of this occurrence are pelitic metasedimentary and subordinate andesitic metavolcanic strata of the Jurassic or older Mesozoic Hazelton Group, which is underlain and locally intruded by the Triassic Texas Creek Granodiorite; and the Eocene Hyder Quartz Monzonite, which intrudes the Hazelton and Texas Creek rocks (Smith, 1977; Koch, 1996). Maas and others (1995, p. 235, 246) describe the occurrence as mineralized float boulders of brecciated Hazelton andesite containing massive bands and veinlets of sphalerite, galena, and minor(?) pyrite and chalcopyrite. The sulfides carry silver and a trace of gold. Intense silica and carbonate alteration has accompanied brecciation and mineralization. Lead-isotope studies of galena from this occurrence (Maas and others, p. 235) indicate that the mineralization is Jurassic in age, contemporaneous, at least in part, with island-arc volcanism in Hazelton time (Alldrick, 1993).
Age: Lead-isotope studies of galena from this occurrence (Maas and others, 1995, p. 235) indicate that the mineralization is Jurassic in age, contemporaneous, at least in part, with island-arc volcanism in Hazelton time (Alldrick, 1993).
Alteration: Intense silica and carbonate alteration of brecciated andesite hostrock.

Commodities (Major) - Pb, Zn; (Minor) - Ag, Au, Cu
Development Status: None
Deposit Model: Polymetallic veins

Other Databases

Link to USGS - Alaska:	BC085

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References