Unnamed (south of Finger Glacier)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Pb; Ti
Other commodities Ag; Cu; Ni; Te
Ore minerals altaite; galena; ilmenite

Geographic location

Quadrangle map, 1:250,000-scale MF
Quadrangle map, 1:63,360-scale B-4
Latitude 58.494
Longitude -137.089
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is at 4100-foot elevation about 3.9 miles northwest of Mt. Marchainville and on the south side of the head of Finger Glacier. The location is accurate to about 0.1 mile based on transposition of sample number 43 of Rossman (1963, B 1121-F) to the 1961 edition of the Mt. Fairweather B-4 quadrangle. Location number 41, also Rossman (1963), is about 0.1 mile southwest of number 43. The location is essentially the same as number 12 (p. C111) of Kimball and others (1978) shown, incorrectly, as their location 13 on plate III.

Geologic setting

Geologic description

The occurrence is in layered gabbro of the Crillon-La Perouse intrusion about one-half mile from its southwestern contact (Brew and others, 1978). The country rock at the contact is hornblende and biotite schist. Both schistosity and intrusive layering in this vicinity mainly strike northwest and dip 45-65 degrees northeast (Rossman, 1963).
Possibly two distinct deposit types are represented in the area. At Rossman's site number 43 cumulus(?) layers rich in ilmenite contain as much as 2.5 percent of ilmenite; at nearby site number 41, heavy mineral sulfide-rich(?) concentrates contained lead, copper, nickel, and a trace of silver. Titanium was negligible at site 41. The mineralogy is uncertain, but lead should be present as a separate phase. Galena is possible, as is a lead telluride, altaite, which occurs in the Brady Glacier deposit (MF003).
Geologic map unit (-137.090916313344, 58.4936352728598)
Mineral deposit model Bushveld Fe-Ti-V (Cox and Singer, 1986; model 3). Ilmenite cumulate segregations at Rossman's (1963) site 43; uncertain lode in layered mafic intrusion at locality number 41, also Rossman.
Mineral deposit model number 3
Age of mineralization Tertiary.

Production and reserves

Workings or exploration Surface outcrops of a 10-foot thick layer at locality number 43 contain as much as 2.5 weight percent ilmenite in four samples (Rossman, 1963, table 6). At nearby site number 41 (table 7) spectrographic analyses of heavy mineral concentrates from locality indicated copper, nickel, lead, and a trace of silver.
Indication of production None
Reserve estimates No reserves assigned, only minor concentration of ilmenite in 10 foot layer at Rossman's (1963) location number 43. Locality of number 41 is a mineralogic curiosity of unknown significance.

Additional comments

Chugach terrane. The sites are in Glacier Bay National Park and Preserve.

References