Baker County Oregon Gold Production |
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CRACKER CREEK DISTRICT
The Cracker Creek district is between lat 44°48' and 44°54' N. and long 118°03' and 118°17' W., north of Sumpter.
The most important lode in this district and in Oregon, the North Pole-Columbia, was discovered in 1887, and it produced about $9 million in gold (Oregon Dept. Geology and Mineral Industries, 1939, p. 34). From 1907 through 1959 a total of 189,389 ounces of gold was recorded from the district.
The country rock in the district is the Elkhorn Ridge Argillite, which probably is of Permian and Late Triassic age. Cutting this argillite is the North Pole-Columbia lode, a vein system that trends northwest to east and continues unbroken for a distance of 5 miles (Lindgren, 1901, p. 658). The vein material consists of quartz, arsenopyrite, pyrite, and some chalcopyrite. Most of the gold occurs in the fine arsenopyrite (Parks and Swartley, 1916, p. 61). Comb structure is common, and some of the earlier minerals are crushed and shattered indicating some movement along the fissure system during deposition.
EAGLE CREEK DISTRICT
The Eagle Creek district is between lat 44°49' and 45°05' N. and long 117°00' and 117°45'- W., in the southern end of the Wallowa Mountains. The boundaries of this district overlap those of the Cornucopia district, and rightly so, for the gold-bearing gravels of the Eagle Creek district were derived from the Cornucopia stock.
Mining began in this district in the early 1860's when placers along Eagle Creek were worked. Those along Paddy Creek were worked also, but most of the gold production was from lodes and some was a byproduct of copper ore. The Sanger mine, the largest producer in the district, yielded an estimated $l1/2 million in gold from auriferous quartz veins (Lindgren, 1901, p. 738). The total early production of the district was estimated at $1,687,400 (about 82,000 ounces) in gold (Lindgren, 1901, p. 738-739). Total recorded production from 1931 through 1951 was 5,782 ounces of lode gold and 69 ounces of placer gold; from 1952 through 1959, no production was recorded.
The country rock of the area is chiefly Triassic greenstone and limestone cut by granitic and diabasic dikes (Gilluly and others, 1933, p. 63). The veins contain pyrite, chalcopyrite, sphalerite, galena, and free gold in a gangue of quartz and some calcite.
GREENHORN DISTRICT
The Greenhorn district is between lat 44°33' and 44°44' N. and long 118°25' and 118°32' W. in Baker and Grant Counties.
Both silver and gold veins were mined in the district before 1910. The Bonanza, the chief mine, produced $1% million in gold before 1904; it operated only sporadically from 1904 through 1916 (Parks and Swartley, 1916, p. 39). After 1930 the bulk of production was from placers. The total gold production of the district through 1959 was 89,200 ounces from lodes and 10,382 ounces from placers.
The following summary of the geology of the district is taken from "Oregon Metal Mines Handbook" (Oregon Department of Geology and Mineral Industries, 1939, p. 52-53). The district, which is on the eastern lower slopes of Vinegar Hill, is underlain by greenstone, argillite, serpentine, and granodiorite, and is surrounded by younger lava flows of Tertiary age. The granodiorite was intruded into the greenstone and argillite, and the ore deposits probably were emplaced during the closing stages of the intrusion. The deposits in the Bonanza mine and its vicinity are in argillite; those near the town of Greenhorn are in greenstone. The ores contain mostly gold and silver, but varying amounts of copper and lead are locally present.
Placers near Winterville, Parkerville, and McNamee Gulch were successfully worked. The value of boulders of silicified Tempskya (Cretaceous) "fern wood" in Eocene (?) gravels exceeded the value of the gold (T. P. Thayer, written commun., 1962).
LOWER BURNT RIVER VALLEY DISTRICT
The Lower Burnt River valley district, which includes Weatherby, Gold Hill, Durkee, Chicken Creek, and Pleasant Valley, is between lat 44° 17' and 44°43' N. and long 117° 10' and 117°41' W., along Burnt River in southern Baker County.
The lode mines in this district were worked in the early 1880's, and the placers probably were worked earlier. Small production from the Weatherby area was maintained until 1955; however, most of the production was in early days, when no accurate records were kept. Some of the major lode mines were the Gold Ridge, Gleason, Little Bonanza, and Little Hill. Estimates of early lode production total $928,000 in gold (about 45,000 ounces) (Lindgren, 1901, p. 765; Oregon Department of Geology and Mineral Industries, 1939, p. 67-71). Total production for the district through 1959 was at least 50,000 ounces of lode gold and 3,500 ounces of placer gold. Production data for placers are reliable only for the period since 1932.
Slates, schists, and limestones of possible Triassic age (Lindgren, 1901, pi. 64) are cut by a mass of granodiorite, diorite, and quartz diorite. The sedimentary rocks strike N. 70°-80° E. and dip steeply to the north (Lindgren, 1901, p. 763). Associated with the intrusive masses are discontinuous small quartz veins that are rich in gold.
Nearly all the gulches and streams that drain into the Burnt River in this district contain auriferous placers.
MORMON BASIN DISTRICT
The Mormon Basin (Dixie Creek, Rye Valley, Malheur) district is between lat 44°22' and 44°31' N. and long 117°23' and 117°40' W. in southern Baker County and northern Malheur County.
As early as 1863 placers were mined in the Rye Valley area and were credited with a production of $1 million in gold (Swartley, 1914, p. 228). Although quartz veins were known in the district in the early days, their gold production was not significant until after 1900; it was valued at about $214 million for the period 1906 to 1916 (Oregon Department of Geology and Mineral Industries, 1939, p. 76). About half of this was from the Rainbow, the largest gold mine in the district, and, from 1913 to 1915, the most productive in the State (Gilluly and others, 1933, p. 38). The district reported only small production from 1915 through 1948, and it was idle from 1949 through 1959. Total gold production through 1959 was about 177,500 ounces from lode mines and 56,200 ounces from placer workings.
Gilluly, Reed, and Park (1933, p. 31-49) discussed in some detail the geology and mines of the Mormon Basin area. The oldest rocks exposed are quartzite, quartz schist, slate, greenstone, and chlorite schist of unknown age. These were intruded by masses of gabbro, dunite, pyroxenite, and harzburgite altered for the most part to greenstone, amphibolite, serpentine, and talc. These igneous rocks have been highly sheared and are foliated. A large mass of quartz diorite makes up Pedro Mountain, a prominent landmark, and there are smaller bodies of this same rock throughout the district. The lower parts of the basin are covered by Tertiary stream deposits interbedded with dacite and andesite flows. The gold deposits are in veins in pre-Tertiary rocks near the quartz diorite masses. Vein minerals are quartz, ankerite, and fuchsite as gangue and pyrite, arsenopyrite, galena, sphalerite, polybasite, hessite, tetrahedrite as ore minerals.
