Production records show dry ore shipments to both the Bunker Hill Smelter and the Tacoma Smelter. Tacoma reported a total of 203 tons of ore received between June 1920-April 1924, with average returns of 33.8 oz/ton silver (Ag) and 1.02% copper (Cu). The Bunker Hill Smelter handled the bulk of ore shipped from the Bayhorse Mine from 1920-1925; 4,692 and 1,595 tons of ore were shipped to Bunker Hill, with 138,710.97 ounces Ag recovered, showing an average of 29.56 oz/ton. Ore shipment records from 1984 showed 5,088 tons of ore shipped, but no average grades were recorded.
The Bayhorse Silver Mine is situated on a mineralized portion of a heavily faulted series of volcanic rocks. The lithologies range from coarse grain andesite to fine grain rhyolite with various intrusives. The mineralized zone occurs in both the highly silicified portion of the andesitic member and in small fractures in the hard, flinty rhyolite. The ore body is generally tabular to trough-like in shape and is transversed by veinlets and stringers of an arsenic rich variety of tetrahedrite, tennantite. There is silver, lead and zinc associated with and combined with copper, arsenic, and vanadium rich minerals, rather than the more common association with galena and sphalerite. There is also azurite and malachite staining on the walls of the excavated stopes. Additional minerals include the less common minerals enargite, dufrenoysite and cuprodesclosite. These minerals are roughly described as copper arsenic sulphides, and are indicative of the extent
BAYHORSE MINE - Oregon
History and Previous Exploration/Development Efforts
The Bayhorse Silver Mine composed of 21 unpatented and three patented claims (480 acres) operated from 1920-1925. Underground development consisted of a 500 foot drift that was driven on a mineralized structure. The drift followed the vein up approximately 80 feet and a large stope was excavated. In 1983, Cash Industries ran a drift on the same level as the stope, 485 feet in to the excavated area. Sunshine Mining Company and Homestake Mining Company conducted exploration on the property until from 1980-1984. The property has been dormant since 1984.
and complexity of mineralization in the area. The body of mineralization is bounded by fine grained fault gouge on all four sides, as well as the top and bottom, indicating that the ore exists as a structurally bound segment of an original body of rock. It is has not been determined if the ore existed pre faulting and is present in the continuation of the lithologic units, however, the degree of impermeability of the fault gouge is such that it would seem to preclude secondary, post movement mineralization.
The distribution of mineralization on the Bayhorse Silver Mine is controlled by three main faults, along with numerous secondary planes of movement. Earlier reports indicated that the northern extent of the mineralized zone terminates against a thick, gouge zone extending to a maximum of 5 feet. The rock is described as a fine-grained cataclasite comprised of fragments of red andesite and darker rhyolite of the hanging wall rock. The fault dips 60º to the north parallel to the dip of the bedding planes. The Sunshine fault strikes N15ºW and dips 20-25º to the south. This fault holds the ore body in the hanging wall and has an apparent normal offset of approximately 260 feet. The Sunshine Fault forms the floor of the previously mined ore body. A shallowly dipping fault zone striking N40E forms the roof of the earlier mined ore body as evidenced by slickenslides, which show down dip movement in the hanging wall of the system. This fault has not been assigned a proper name. The Osburn Fault lies to the west of the Bayhorse Silver Mine. The fault strikes approximately N15W and is steeply dipping to near vertical. The Ore body terminates against a fine grain, greenish fault gouge related to the fault on its western boundary. The Osburn Fault interactions in the area indicate a complex history of movement, which led to the present juxtaposition of distinct lithological members. It is suggested that the dominant faults are post mineralization and have subsequently offset an existing, more extensive zone of mineralization.
Proposed Future Exploration – Phase I
Phase I is a recommended program that would consist of implementing an orientation survey, for soil and rock geochemistry and geophysics, including Magnetometer/VLF, SP and IP Surveys. To determine viable methodology of operations, geologic mapping and sample Geochemistry under the recommended exploration plan would be carried out over the entire property utilizing early stage core drilling. This proposed work is designed to accurately assess the property to determine if there exists the possibility of a massive sulfide deposit and to justify if further work as outlined in Phase II is necessary and determine which techniques of data acquisition are appropriate for the Bayhorse Property. An attempt will be undertaken to reopen the underground working for purposes of examination, mapping and samplin.
Orientation survey over surface of known mineralized zone and outcrops – Phase II
The proposed orientation survey would establish a working grid system, which will allow for accurate data acquisition, as well as provide the initial Geochemical and Geophysical data to determine which methodology is applicable; a) mapping; b) geochemical surveys; c) geophysical evaluation; d) detailed geologic mapping on surface and open underground rock units and structure including additional rock geochemistry testing; f) Soil geochemical testing of property; g) grid soil sample and assay1000 soil samples total distance of 26 line miles; Magnetometer /VLF over property; SP Survey over property; IP Survey over selected SP Lines of 10 line miles. Predicated on these results, the decision will be made with regard to a comprehensive diamond drilling program.
Work Begins On Bayhorse Mine