Portland

Prospect, Inactive

Commodities and mineralogy

Main commodities Cu; Pb; Zn
Ore minerals chalcopyrite; galena; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale BC
Quadrangle map, 1:63,360-scale A-1
Latitude 56.022
Longitude -130.053
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Portland prospect is in Section 35 at an elevation of about 2200 feet on a northwest-facing mountainside overlooking the confluence of Salmon River and Texas Creek, and about 0.7 mile due east of the ruins at Ninemile (Elliott and Koch, 1981, p. 17, loc. 70).
Also see Additional Comments field, below.

Geologic setting

Geologic description

The country rocks in the area of the Portland prospect are the Triassic Texas Creek Granodiorite, which underlies and locally intrudes pelitic metasedimentary and subordinate andesitic (greenstone) metavolcanic strata of the Jurassic or older Mesozoic Hazelton Group; the Eocene Boundary Granodiorite, which intrudes the Hazelton and Texas Creek rocks; and still-younger Tertiary lamprophyre dikes, which cut all the other rocks (Smith, 1973, 1977; Koch, 1996).
Buddington's (1929, p. 84) description of the Portland group ambiguously includes information about the Hobo group, which he also describes separately (p. 84-85). (See Additional Comments field, below). The deposit is in greenstone and slate cut by a dike of granodiorite porphyry. On the Portland group, Buddington describes only a quartz vein along the slate-dike contact that contains many inclusions of the country rocks and which was exposed in an open cut. On the Hobo group, he describes a 2-3 foot quartz vein in the dike, and a 2-foot quartz vein in slate that was explored by a 15-foot adit and traced for 1500 feet by pits and surface exposures. The slate-hosted vein contains sparsely disseminated pyrite, galena, and sphalerite, and a little chalcopyrite. The slate also contains other quartz veins and stringers.
Geologic map unit (-130.054704449363, 56.0217048146327)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c

Production and reserves

Workings or exploration Quartz vein in slate was explored by pits and a 15-foot adit, probably in the 1920s.
Indication of production None

Additional comments

The Portland group was originally staked in 1919.
Buddington's (1929, p. 84) description of the Portland group ambiguously includes information about the adjoining Hobo group, which he also describes separately (p. 84-85). This record (BC070) summarizes Buddington's ambiguous description of the Portland(-Hobo) group, whereas BC071 summarizes Buddington's separate description of the Hobo group.

References