Hobo

Prospect, Inactive

Alternative names

Swede

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; pyrite; pyrrhotite; sphalerite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale BC
Quadrangle map, 1:63,360-scale A-1
Latitude 56.021
Longitude -130.044
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Hobo prospect, at the eastern edge of Section 35, is at an elevation of about 2400-2450 feet on a northwest-facing mountainside overlooking the confluence of the Salmon River and Texas Creek. It is about 1.0 mile east of the ruins at Ninemile (Elliott and Koch, 1981, p. 17, loc. 71). The location is accurate within about a quarter of a mile.
Also see Additional Comments field, below.

Geologic setting

Geologic description

The country rocks in the area of this site are pelitic metasedimentary and subordinate andesitic (greenstone) metavolcanic strata of the Jurassic or older Mesozoic Hazelton Group, which is underlain and locally intruded by the Triassic Texas Creek Granodiorite; the Eocene Boundary Granodiorite, which intrudes the Hazelton and Texas Creek rocks; and still-younger Tertiary lamprophyre dikes, which cut all of the other rocks (Smith, 1973, 1977; Koch, 1996).
The deposit (Buddington, 1929, p. 84-85) consists of mineralized (pyritized) greenstone containing veins or veinlike replacements of pyrite, pyrrhotite, and sphalerite, and smaller amounts of chalcopyrite, galena, and arsenopyrite. Early assays show some gold and silver, generally in small and variable amounts. Another vein in greenstone contains pyrite, pyrrhotite, and a little arsenopyrite in quartz gangue; these sulfides carry about 0.2-0.58 oz Au per ton. Nearby quartz veins in a fissure zone in greenstone carry pyrite, galena, and sphalerite.
Elliott and Koch (1981, loc. 71) describe the deposit as greenstone that contains mineralized zones with seams, fracture facings, and veins of the same sulfides described by Buddington. Their report also refers to quartz veins and disseminated sulfides; to quartz and calcite as the principal gangue minerals; and to a reported 9 oz of Au per ton in some samples.
Concentrated sulfide samples from a shear zone on the Hobo prospect yielded an Eocene lead-isotope age (Maas and others, 1995, p. 254). The deposit, however, is similar in mineralogy, structural setting, and hostrock to isotopically dated Jurassic deposits nearby in the Hyder district (see, for example, BC065, BC067). The lode thus may be polygenetic, originating as a 'disseminated' deposit during Jurassic (Hazelton) island-arc volcanism (Alldrick, 1993), and then partly remobilized into shear zones during emplacement of the Boundary Granodiorite.
Geologic map unit (-130.045704413896, 56.0207054877476)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c
Age of mineralization Concentrated sulfide samples from a shear zone on the Hobo prospect yielded an Eocene lead-isotope age (Maas and others, 1995, p. 254). The deposit, however, is similar in mineralogy, structural setting, and hostrock to isotopically dated Jurassic deposits nearby in the Hyder district (see, for example, BC065, BC067). The lode thus may be polygenetic, originating as a 'disseminated' deposit during Jurassic (Hazelton) island-arc volcanism (Alldrick, 1993), and then partly remobilized into shear zones during emplacement of the Boundary Granodiorite.
Alteration of deposit Greenstone country rock is impregnated with sulfide minerals.

Production and reserves

Workings or exploration
Property explored by open cuts, probably mainly in the 1920s.
Early assays of sulfide samples show 0.2-0.58 oz Au per ton. Some samples reported to carry as much as 9 oz Au per ton.
Indication of production None

Additional comments

The Hobo group was originally staked in 1919.
The Swede group (Buddington, 1925, p. 78) is probably the same as the Hobo group, but has also been referred to in descriptions of the Portland and Daly-Alaska properties (Cobb, 1978, p. 73).
Also see BC070.

References