By A. H. KOSCHMANN and M. H. BERGENDAHL - USGS 1968
Yavapai County, in the central part of Arizona, ranks first in the State in gold production through 1959.
The production by ounces is as follows:
|Prior to 1900||477,703||193,500|
|1900 to 1934||1,934,447||33,204|
|1935 to 1959||1,064,000||40,100|
The Jerome (Verde) district is the largest gold producer, having contributed about 1,565,000 ounces to the total lode production.
Though mineral deposits were known in this area long before the Civil War, the first prospectors were Union soldiers with mining experience from California (Wilson and others, 1934, p. 23). Placers at Rich Hill were discovered in 1862 and those along Hassayampa and Lynx Creeks were discovered in 1863 (Lindgren, 1926, p. 2-5).
Silver ore, first discovered in the Big Bug district in 1870, was found at other localities in Yavapai County in the 1870's. Claims were located in the Jerome district in 1876.
The northern part of Yavapai County is in the plateau region, and the southern part is in the mountain region, which consists of a series of short mountain ranges of the fault-block type that trend north-northwest and are separated by broad valleys filled with fluvial and lacustrine deposits.
The mountains consist chiefly of Precambrian metamorphic and igneous rocks, which are intruded locally by stocks, plugs, and dikes of granitic rocks of Late Cretaceous or early Tertiary age. Large areas are covered by volcanic rocks of Tertiary and Quaternary age.
The ore deposits, which are in the mountain region, consist of veins and replacement deposits of Precambrian age and veins of Mesozoic or early Tertiary age. Placer deposits have also been important.
AGUA FRIA DISTRICT
The Agua Fria district is southeast of Prescott along the headwaters of the Agua Fria River about 4.5 miles northeast of Mayer. Both gold and silver are byproducts of copper ore.
The Stoddard mine in this district is one of the earliest locations in Arizona but no dates of discovery or location are known (Lindgren, 1926, p. 148). The district was active during World War I and into the early 1920's - probably its period of greatest production. From 1936 through 1957 the mines were operated intermittently. Total gold production through 1959 was about 12,710 ounces.
The rocks exposed in the district are chiefly schists of the Precambrian Yavapai Series, which are intruded by the Precambrian Bradshaw Granite. The Yavapai Series includes many quartz lenses and bodies of fissile quartz porphyry. The Precambrian rocks are capped locally by volcanic flows and tuffs of Tertiary age (Lindgren, 1926, p. 146-147).
The ore deposits are replacement bodies of quartz, pyrite, and chalcopyrite, and tetrahedrite in the schists.
BIG BUG DISTRICT
The Big Bug district, on the northeast slope of the Bradshaw Mountains, is about 12 miles east-southeast of Prescott. Copper, gold, silver, lead, and zinc are obtained from a variety of ore deposits in the district.
Wilson, Cunningham, and Butler (1934, p. 39) referred to activity at the Big Bug mine as early as 1866, and other properties were producing gold and silver from oxidized ores before 1870. After a period of decline, some mines were reopened in the late 1890's and maintained a small sporadic annual output through 1933.
The tempo of mining increased from 1934 through 1959 mainly because of expanded operation of the Iron King mine. Gold placers were highly productive during the 1880's (Wilson, 1952, p. 48-50) and from 1933 through 1942, after which they declined in importance.
Total gold production from 1867 through 1959 was about 627,000 ounces, of which about 42,700 ounces was from placers.The Yavapai Series, which here consists of inter-layered sedimentary rocks and volcanic tuffs and breccias, was intruded by a variety of Precambrian granitic rocks - gabbro, diorite, granodiorite, and granite, and by dikes of rhyolite porphyry (Lindgren, 1926, p. 126-127; Anderson and Creasey, 1958, pi. 1). Tertiary volcanic rocks younger than the ore deposits locally form a cover.
Lindgren (1926, p. 127) recognized four classes of ore deposits in the district; however, the lead-zinc-silver veins of the Iron King mine have yielded the most gold, and the gold vein of the McCabe-Gladstone property has probably been the second largest gold producer.
The Iron King deposit is a system of 12 massive sulfide veins oriented en echelon in a mylonitized shear zone in the Spud Mountain Volcanics of the Precambrian Yavapai Series (Creasey, in Anderson and Creasey, 1958, p. 156-169). The wallrock is so intensely altered by hydrothermal introduction of quartz, sericite, and pyrite that in places the nature of the original rock cannot be determined.
Two groups of veins are recognized in the deposit: well-defined massive sulfide veins, from which all but a few tons of the total ore has been mined, and poorly defined veins, chiefly of pyrite, ankerite, and quartz. The massive sulfide veins comprise thin layers of fine-grained pyrite, sphalerite, chalcopyrite, arsenopyrite, galena, and tennantite. Quartz and ankerite are the major gangue minerals. Gold is in the pyrite, and silver is probably in the tennantite.
The McCabe-Gladstone is one of several mines on the 14,000-foot-long Silver Belt-McCabe vein, a mineralized shear zone in the breccia facies of the Spud Mountain Volcanics. Ore occurs as discontinuous lenses or pods of coarsely crystalline drusy masses of sulfides, with numerous open vugs. The mineralogy of the ore is variable. Silver and lead are abundant in the ores at the north end of the vein.
Toward the south end the ores are more complex and contain lead, zinc, iron, silver, copper, and gold. The McCabe-Gladstone mine, which is at the south end of the vein, is in ore composed of arsenopyrite, pyrite, chalcopyrite, and quartz. The gold and silver are in the sulfides (Creasey, in Anderson and Creasey, 1958, p. 169-171).
BLACK CANYON DISTRICT
The Black Canyon district is in southeastern Yavapai County between the eastern foothills of the Bradshaw Mountains and the Agua Fria River, at Bumblebee.
The first locations were made probably as early as 1873, but the first record of mineral production was in 1904. The district was active through 1956, with the highest output from 1934 through 1941. Total gold production from 1904 through 1959 was about 46,700 ounces.
A belt about 2 miles wide of Yavapai schist trends northward through the district and is flanked on the east by a narrow mass of diorite and Bradshaw Granite and on the west by Bradshaw Granite. These rocks, which are all of Precambrian age, are overlain in the eastern part of the district by volcanic rocks of Tertiary age (Lindgren, 1926, p. 153).
The gold ore is in Precambrian high-angle veins and in flat veins of a younger age (Lindgren, 1926, p.156-159).
The Precambrian veins contain coarse glassy quartz and small amounts of chalcopyrite, pyrite, galena, sphalerite, and native gold. Aggregates of minute prisms of blue, brown, or colorless tourmaline are associated with the sulfides. The flat veins, which are also found in the Precambrian rocks, consist of quartz with a little pyrite, galena, chalcopyrite, and locally contain sphalerite and proustite. The gold in these veins is probably in the sulfides.
BLACK ROCK DISTRICT
The Black Rock district, about 12 to 15 miles northeast of Wickenburg, was prospected for copper and silver in the 1870's, but according to meager records the deposits were not developed until 1900 or later (Wilson and others, 1934, p. 62-65).
Through about 1932 the district is credited with a gold production of $195,000 (9,438 ounces), most of which came from the Gold Bar (O'Brien) mine (Elsing and Heineman, 1936, p. 103). From 1932 through 1955 the district produced 2,754 ounces of gold, of which at least 99 ounces was placer gold. The total through 1959 was about 12,190 ounces.
The principal rocks of the region are schist and granite of Precambrian age, volcanic rocks (chiefly andesite) of Cretaceous (?) and Tertiary age, and local remnants of basalt of Quaternary age (Arizona Bureau of Mines, 1958).
The ore deposit in the Gold Bar mine is a fissure vein consisting of coarse glassy quartz with pyrite and free gold. In the oxidized zone the quartz is cellular; its cavities are filled with hematite and limonite formed from pyrite, which is common in the deeper zones. Gold occurs as fine to medium-coarse particles, both in the quartz and with the iron minerals (Wilson and others, 1934, p. 63-64).
The Eureka (Bagdad) district is in western Yavapai County, 42 miles west of Prescott. Most of the mines are near Bagdad in the southwestern part of the district.
Although the district is noted mainly for copper, its deposits were mined originally for silver, gold, and lead. The first claims were located in 1880, and mining began in 1887. Until 1917 most production was from ores rich in gold and silver, with subordinate lead and zinc, from the Hillside mine.
Copper minerals were known in the district as early as 1882; however, sporadic exploration through the early 1900's failed to disclose any significant copper ore bodies until 1929 when the Bagdad mine began operations. Gold and silver production from the Hillside mine and several smaller properties continued until 1942, when the Hillside mine was closed.
Meanwhile the Bagdad mine expanded due to the demand for copper during World War II. Large-scale activity continued after the war. The Hillside mine was reopened during 1948-51; open-pit mining increased the Bagdad mine production after 1947; and other properties were developed to mine tungsten and zinc. Copper output at the Bagdad mine continued to be significant through the 1950's, and in 1959 it was the largest copper producer in the county.
Total gold output of the district from 1887 through 1951 was 59,787 ounces, of which 58,748 ounces is attributed to the Hillside mine (Anderson and others, 1956, p. 46, 84). From 1952 through 1959 the district produced only 179 ounces of gold. The copper ores at the Bagdad mine yielded insignificant amounts of gold.
Most of the bedrock in the Eureka district is of Precambrian age and consists of metamorphosed volcanic and tuffaceous sedimentary rocks and intrusive masses of rhyolite, gabbro, anorthosite, quartz diorite, diabase, alaskite, granodiorite, and granite. Rhyolite tuff of Cretaceous (?) or Tertiary (?) age unconformably overlies the Precambrian rocks in the southwestern corner of the area, and small stocks, plugs, and dikes of quartz monzonite, quartz monzonite porphyry, and diorite porphyry, slightly younger than the rhyolite tuff, are scattered throughout the older terrain.
A thick section of Tertiary and Quaternary clastic sedimentary rocks intercalated with basalt and rhyolite flows and tuffs caps the mesas and overlaps the older rocks (Anderson and others, 1956, p. 6-29). The Precambrian rocks show effects of folding, dynamic and thermal metamorphism, and several periods of faulting. Faulting continued during at least three periods in post-Precambrian time, when some of the major faults related to the mineral deposits were formed (Anderson and others, 1956, p. 29-39).
The gold-silver-zinc-lead deposit at the Hillside mine is a fissure vein in the Hillside fault, which trends N. 10 W. to N. 25 E. and dips steeply to the west in the mine vicinity. The mineralization was related to the quartz monzonite intrusions and occurred during Cretaceous or early Tertiary time. Postmineral faulting, resulting in gaps and overlaps of ore, is a factor to be considered in exploiting these deposits.
The hypogene vein minerals are pyrite, arsenopyrite, galena, sphalerite, argentite, chalcopyrite, freibergite, and tetrahedrite in a gangue of quartz. Most of the gold is associated with pyrite and arsenopyrite. The upper part of the vein is oxidized to limonite-stained quartz and variable amounts of gold, silver, cerargyrite, cerus-site, malachite, chalcanthite, and goslarite (Anderson and others, 1956, p. 77-79).
HASSAYAMPA-GROOM CREEK DISTRICT
The Hassayampa-Groom Creek district is on the western slopes of the Bradshaw Mountains, 6 miles south of Prescott.
Gold placers were discovered in 1864 along the Hassayampa River, and shortly afterward many quartz veins were found. Considerable gold and silver was extracted from the shallow oxidized parts of these veins, and after 1895 the primary sulfide ore was mined for gold, silver, copper, lead, and zinc (Wilson and others, 1934, p. 41).
The placers were worked most intensively between 1885 and 1890; thereafter, operations were carried out on a small scale (Wilson, 1952, p. 52). From 1953 through 1959 the district produced only a few ounces of gold per year from lodes and placers.
Total gold production through 1959 was about 127,000 ounces - 18,700 ounces from placers and 108,300 ounces from lodes. Schists of the Yavapai Series and the Bradshaw Granite, the oldest rocks of the district, were intruded by several small masses of diorite and granodiorite and dikes of rhyo-lite porphyry, all of Precambrian age (Lindgren, 1926, p. 114-115, pi. 2).
Most of the ore deposits are in fissure veins in the schist, a few are in the granite and diorite. The ore consists of pyrite, arsenopyrite, sphalerite, galena, chalcopyrite, and local tetrahedrite, in a gangue of quartz and a little carbonate. Gold is associated with quartz and sulfides, and in some deposits, with specularite. Some veins are of Precambrian age, others are of probable Tertiary age (Lindgren, 1926, p. 114-126).
The Jerome (Verde) district is on the eastern slope of the Black Hills in northeast Yavapai County just west of the Verde River. Both gold and silver have been produced as byproducts of copper mining from the two major mines in this district - the United Verde and the United Verde Extension.
Centuries ago the copper ores at Jerome were utilized by Indians for jewelry and dyes. In 1582 and 1598 Spanish explorers visited the deposits and located claims, though they did not work them. The deposits remained unnoticed and undeveloped until their rediscovery in 1875 by U.S. Army troops.
In 1876 prospectors entered the area, and by 1882 the newly organized United Verde Copper Co. began consolidating the numerous claims and later became the largest producer of the district. Oxidized ores rich in gold, silver, and copper were mined in 1883-84, but by the end of 1884 the ore was exhausted and the price of copper dropped, so that work was suspended at the United Verde property until 1888.
Prospecting elsewhere in the district in the early 1900's was successful, and for a time several small mines were active. The United Verde Extension Gold, Silver, and Copper Mining Co. was organized in 1899, and under its successors it became the second largest mine of the district.
In the early 1900's the United Verde Extension Co. explored extensively, first to the southwest and later east of the prospering United Verde property. Most of these efforts were fruitless; nevertheless, work continued until the company was on the verge of collapse. Finally in 1914, a rich chalcocite ore body was found on the 1,200 level, and in 1916 a much larger ore body was found. The company operated on a large scale until 1938 when the deposit was mined out and the mine was closed.
The United Verde mine continued its underground operations until 1931, after which open-pit mining was the chief activity. Depletion of reserves finally forced the mine to close in 1953 (Anderson and Creasey, 1958, p. 84-90).
The large-scale copper mining yielded a total of about 1,565,000 ounces of byproduct gold from 1883 through 1951 (Anderson and Creasey, 1958, p. 101). Total gold production from 1883 through 1959 was about 1,571,000 ounces.
Most of the central and southern parts of the Jerome district are underlain by slate, phyllite, schist, gneiss, and granulite that make up the Yavapai Series of Precambrian age. These rocks are intruded by numerous irregular bodies of quartz porphyry, gabbro, quartz diorite, and granodiorite, also of Precambrian age.
Paleozoic sedimentary rocks, which cover parts of the northern half of the district, overlie the Precambrian rocks unconformably and range in age from Cambrian to Penn-sylvanian or Permian. Rocks of Mesozoic age do not occur in the district; a thick section of lava flows and intercalated sedimentary rocks of Pliocene (?) age and lake deposits of late Pliocene and Pleistocene age overlap the older rocks (Anderson and Creasey, 1958, p. 8-61).
The Precambrian rocks were deformed during several periods of faulting and folding. Later faulting, accompanied by tilting, displaced the Paleozoic and Cenozoic rocks (Anderson and Creasey, 1958, p. 62-83). The important ore deposits of the district are massive sulfide deposits of Precambrian age. At the United Verde mine the main ore body was a pipelike mass of pyrite, chalcopyrite, sphalerite, quartz, and carbonates that replaced quartz porphyry and tuffaceous sedimentary rocks.
The deposits of the United Verde Extension mine were buried beneath a cover of Paleozoic and Tertiary sedimentary rocks. Ore consisted of elliptical masses of chalcocite in Precambrian rocks. Massive sulfide, similar in composition to the United Verde ore body, underlies the chalcocite. In both mines the sulfide ore bodies were overlain by oxidized zones containing iron oxides, malachite, azurite, chrysocolla, gold, silver, and native copper (Anderson and Creasey, 1958, p. 103-145).
LYNX CREEK-WALKER DISTRICT
The Lynx Creek-Walker district is about 7 miles southeast of Prescott. Lynx Creek is one of the most productive placer streams in the State; moreover, lode mines in the Walker camp have yielded considerable gold, silver, copper, and lead.
The placers were discovered by a party of California miners in 1863, and as they worked upstream they found the gold-bearing veins of the Walker camp (Lindgren, 1926, p. 108-109). The richest placers were depleted in the early days, but small and intermittent placer operations continued for many years. From 1927 through 1941 large-scale dredging operations were successful, but from 1942 through 1959 the placer mining was desultory and was carried out on a small scale.
In the Walker camp only oxidized ore was mined in the early years and was worked in arrastres. Deep mining into the sulfide zone presumably was begun some time before 1910. Lode production probably was never very large, and it fluctuated considerably but was almost continuous from 1905 through 1952.
According to Lindgren (1926, p. 109) the placer output through 1924 was about $1 million, most of which was extracted in the early years. Wilson (1952, p. 39, 42) reported that production before 1881 was estimated at $1 million (48,379 ounces), and from 1900 to 1949 it was about $1 million, mostly during 1933-42. Total gold output of the district through 1959 was about 140,000 ounces: 97,000 ounces from placers and 43,000 ounces from lodes.
Underlying the district are schists of the Yavapai Series and the Bradshaw Granite intruded first by a granodiorite stock and later by a number of rhyolite porphyry dikes. The ore deposits are in sulfide-bearing quartz veins that transect the granodiorite. Ore minerals are pyrite, sphalerite, chalcopyrite, galena, and tetahedrite. Gold is contained in chalcopyrite, and gold and silver seem to be associated with galena and tetrahedrite. The ores were mined mainly for gold (Lindgren, 1926, p. 111).
The Martinez district is in southwestern Yavapai County in the southeastern Date Creek Mountains a few miles northwest of Congress.
Gold was produced almost entirely from quartz veins and mostly from the Congress mine. The first discoveries were made in 1870, but the ore was not free milling and thus progress was impeded until a cyanide plant was built in 1895. High production was maintained until 1910 (Wilson and others, 1934, p. 69-71).
Except for a span of intensive operation by lessees during 1938-42, the mine was virtually idle from 1910 through 1959. The total minimum gold production of the Congress mine from 1887 through 1959 was about 396,300 ounces.
The eastern Date Creek Mountains consist of coarse-grained granite, intruded by pegmatites, aplites, and basic dikes. The gold deposits are along low-dipping faults in veins that consist of coarse-textured quartz with pyrite and some galena (Wilson and others, 1934, p. 69).
At the Congress mine the most productive veins are within the basic dikes, mostly near their footwalls. Veins in the granite are of lower grade; they carry small amounts of galena and larger amounts of silver (Staunton, 1926, p. 769). Ore has been mined to a depth of 4,000 feet.
The Peck district is in the drainage area of Peck Canyon and Bear Creek, about 20 miles south-southeast of Prescott.
Rich silver ore was discovered in the Peck mine in 1875, and in the following 10 years $1 to $1.5 million worth of silver was mined. Other silver deposits were found in the late 1870's. By 1885 the rich ore of the Peck mine was depleted, and work in the succeeding years was mainly by lessees.
In the early 1900's copper-silver properties were developed which yielded considerable byproduct gold. From 1932 through 1959 the district was for the most part inactive. Total gold production from 1890 through 1959 was about 15,550 ounces.
The area is underlain by Precambrian rocks, chiefly the Yavapai Series, which here includes quartzite and layers of amphibolite, chlorite, and sericite schist. The belt of schist, about 2 miles wide, lies between areas of Precambrian Bradshaw Granite. Porphyry dikes intruded the schist parallel to its strike (Lindgren, 1926, p. 160).
The veins, found in the quartzite and schist, are parallel to the foliation. The rich silver-bearing veins contain a gangue of siderite or ankerite, which near the surface is almost wholly oxidized to limonite. The principal ore minerals are bromyrite and subordinate native silver, but locally the veins contain chalcopyrite and silver-rich tetrahedrite.
The copper-rich ore bodies found in the De Soto mine are overlapping lenses of fine-grained quartz in the chloritic schist of the Yavapai Series. They contain pyrite, chalcopyrite, some sphalerite and galena, and sparse tetrahedrite and arsenopyrite (Lindgren, 1926, p. 161-163). Gold occurs as microscopic grains in the sulfides.
PINE GROVE-TIGER DISTRICT
The Pine Grove-Tiger (Crown King) district is in the heart of the Bradshaw Mountains 40 miles by road southeast of Prescott; the Tiger camp lies immediately south of the Pine Grove camp. The ores, which were very rich in silver and gold near the surface, also contained significant amounts of copper, lead, and zinc.
A few mines in this district were worked as early as 1874, but there is little indication of any significant development until after 1890. The Crown King mine, the most important gold property of the district, was most active between 1893 and 1900 (Lindgren, 1926, p. 168). More recent productive flurries occurred during 1903-23 and 1934-51. The total gold production through 1959 was about 130,275 ounces.
Bedrock in the district consists of Precambrian Yavapai Series and Bradshaw Granite which are intruded by a stock and dikes of granodiorite of Mesozoic or Tertiary age and by younger dikes of rhyolite porphyry and granite porphyry (Lindgren, 1926, p. 21-23, 164-176).
The ore is in veins which are most abundant in the granodiorite; a few extend into the surrounding rocks. The vein minerals are pyrite, chalcopyrite, sphalerite, galena, and some tetrahedrite in a gangue of quartz with a little ankerite and calcite. In some of the sulfide ore, native gold is present. Much of the mined ore was partly oxidized and rich in gold and silver (Lindgren, 1926, p. 164-165).
The Tiptop district is in the southern foothills of the Bradshaw Mountains in southeastern Yavapai County, about 45 miles north-northwest of Phoenix.
The history and production of the district is mainly that of the Tiptop mine (Lindgren, 1926, p. 180). This mine, located in 1875, yielded about $2 million probably all in silver and gold, before 1883, when it was closed. The mine was reopened from 1886 to 1888, but apparently it has been closed since that time.
A small amount of tungsten ore was mined, probably during World War I. Since then the district has been dormant, except for minor activity during the 1930's and early 1950's. Lindgren (1926, p. 180) considered the estimated total production of $4 million somewhat high. Total gold production through 1959 was about 10,000 ounces.
The host rock is the Bradshaw Granite which intruded a north-trending belt of Yavapai Series, exposed just east of the district. The granite is cut by dikes of rhyolite porphyry and is overlain by a remnant of Tertiary lava flows at the south end of the district (Lindgren, 1926, p. 179-180).
The ore deposits are fissure veins in the granite. The principal gangue mineral is fine to coarse quartz, and some druses are coated with chalcedony. The ore minerals, in paragenetic order, are wolframite, arsenopyrite, pyrite, sphalerite, bornite, and galena. Cerargyrite and ruby silver were common in the oxidized ore; antimonial silver minerals and native silver were probably also present. Some veins rich in galena contained gold and some silver (Lindgren, 1926, p.181-182).
WEAVER-RICH HILL DISTRICT
The Weaver-Rich Hill district is in southwestern Yavapai County along the southwestern front of the Weaver Mountains, 5 to 8 miles east of Congress. Both lodes and placers have been important sources of gold in this district.
An accidental discovery of gold nuggets on top of Rich Hill in the early 1860's kindled interest in the area and before long gold placers along Weaver and Antelope Creeks and the lode deposit at the Octave mine were found (Wilson, 1952, p. 43). By 1883 the placers had yielded $1 million in gold, but thereafter the deposits were worked sporadically and were idle from 1952 through 1959.
Little development of the Octave mine was attempted until the perfection of the cyanide process in the 1890's. Between 1900 and 1905 gold and silver ore worth $1,900,000 was mined. Activity declined after 1905, and the mine was closed in 1930.
Under new ownership of the American Smelting and Refining Co., the mine was reopened in 1934 (E. D. Wilson, in Arizona Bureau of Mines, 1938, p. 131) and was worked until December 1942 (Woodward and Luff, 1943, p. 258). Lode production of the district declined sharply in 1943 and was negligible through 1959.
Placers in the district are credited through 1959 with about 104,000 ounces of gold and lodes with about 204,000 ounces, a total of 308,000 ounces. All but about 1,500 ounces of the lode gold came from the Octave mine.
The country rock of the district is mainly granite and quartz diorite with lenses and septa of schist. These rocks are cut by dikes of pegmatite, aplite, and diabase (Wilson and others, 1934, p. 66-68).
The veins in the district occur along low-angle fault zones that are chiefly in the granite, but some are in the schist. The main Octave vein, which is in granitic rocks (Nevius, 1921, p. 123), consists of coarse white quartz that carries irregular masses, disseminations, and layers of fine-grained pyrite, galena, and sparse sphalerite and chalcopyrite and a little native gold. Most of the gold is contained in the galena (Wilson and others, 1934, p. 67, 68).
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