Carson Hill Mining District (Melones Mining District), Calaveras County, California, USAi

Regional Level Types
Carson Hill Mining District (Melones Mining District)	Mining District
Calaveras County	County
California	State
USA	Country

Carson Hill is on the Mother Lode belt in southwestern Calaveras County. The district consists of that portion of the Mother Lode that extends from Carson Flat southeast through Carson Hill to the town of Melones on the Stanislaus River. It has also been known as the Melones district.

History: Carson Hill was named for James H. Carson, a soldier who came to California in 1847 and who discovered gold at nearby Carson Creek in 1848. Within 10 days, Carson and a small company of men reportedly had each taken out 180 ounces of gold, after which they left the area planning to return the following year. By 1849, word had gotten out, and when Carson returned he found the area swarming with miners and little left to claim. He left Carson Hill to prospect the Mother Lode farther south.

Lode gold was first discovered in 1850 at the Morgan mine and many miners soon came to the area. By 1851, the town of Melones had a population of 3,000 to 5,000. It was named for the melon seed-shaped gold nuggets found here. The district was extremely productive then, much of the mineral coming from fantastically rich surface pockets. Gold to the amount of $110,000 was exposed by one blast, and in 1854, a 195-pound mass of gold, the largest ever taken in California, was found here. Telluride minerals were recovered in quantity, but most were lost in unsuccessful attempts to extract the gold.

The Carson Hill mines principal properties were the Calaveras, Finnegan, Melones, Morgan, Reserve, and Stanislaus mines. Other claims that were consolidated with one or more of these mines included the Adelaide, Carson, Enterprise, Iron Rock, Irvine, Kentucky, May Day, Mayflower, McMillan, Mineral Mountain, Point Rock, relief, South Carolina, and Union. Because of the complexity of the history of operations and various consolidations, all have been generally grouped together for this discussion, with only the more important mines being described in any detail.

Lode gold was first discovered in 1850 at the Morgan Mine on Carson Hill. The rich surface ores were easily crushed in hand mortars, and rock too poor for a hand mortar was ground in arrastras. From February 1850 until December 1851, it was reported that about $2.8 million was extracted and unknown sums were stolen (Clark and Lydon, 1962). As much as $110,000 in gold was exposed with a single blast, and in 1854, a 195-pound mass of gold, the largest ever found in North America, was found ("Calaveras Nugget"). The nugget was eventually melted down after being exhibited at the Paris Exhibition in 1856. Telluride minerals were also recovered in quantity, but most were lost in unsuccessful attempts to extract the gold (Clark, 1970).

After the rich shallow ores were exhausted, ore grade and gold production declined. In the late 1850s, G.K. Stevenot took possession of the Morgan Mine and erected a 3-stamp mill, the first quartz mill in the area (destroyed by fire in 1862). The Melones and Stanislaus Mining Company was then organized (with G. K. Stevenot as manager) to work the Melones and Stanislaus claims. By 1865, the two properties had been mined to a depth of 250 feet and a length of 400 feet. The ore was dry ground in a wooden tub-like device, and the concentrates were shipped to New York. Later an eight-stamp mill was erected on the property. In the meantime, the Finnegan Mine on the northeast slope of Carson Hill, which had been discovered in 1857, was active (Clark and Lydon, 1962).

During the late 1860s and early 1870s, the mines were mostly idle, due largely to litigation over the Morgan Mine claims and milling difficulties. In 1869, the Morgan Mine was sold for back taxes of $115.19 to William Irvine. Lack of modern processes, an absence of a cheap labor force, and the necessity for large-scale operations made it expensive to mine and mill the lower-grade ores. Lacking sufficient capital, Irvine deeded the claim to the Morgan Mining Company of which he was a major stockholder. In 1876, the Morgan Mining Company reopened the mine and a tunnel was begun, which in 1878, struck the vein 200 feet below the outcrop. The Morgan Mine was operated intermittently until 1884 when it was acquired by Senator James G. Fair. Due to animosity between Fair and Irvine, Fair closed the Morgan Mine, refusing to allow it to be worked during his lifetime so that Irvine would not profit from his 25% interest (the mine remained closed until 1914 when the Calaveras Consolidated Mining Company bought the Morgan Mine from the Fair estate).
In 1888, an orebody 40 feet wide was discovered on the Calaveras claim. The same year, the Calaveras Consolidated Gold Mining Company, Ltd., was organized to develop the find. It purchased several claims on the Calaveras vein, erected a 20-stamp mill and commenced development. This was the first operation in the area in which large low-grade ore bodies were mined commercially (Clark and Lydon, 1962).

In 1898, the Melones Consolidated Mining Company was organized with Grayson and Boland as principal stockholders. This concern consolidated the Enterprise, Keystone, Last Chance, Melones, Mineral Mountain, Reserve, and Stanislaus claims, and later the South Carolina. Under the superintendency of W.C. Ralston and later W. G. Deveraux, a large amount of development work was done including driving the Melones adit northwestward from the south side of the hill. A new mill was erected just east of the adit, and the first 60 stamps began operation in 1902. The mill was increased to 100 stamps in 1905. This was the first mine on Carson Hill to employ modern technological methods including a large mill with full electrical power that could process large volumes of low-grade ore. Mining and milling costs were lower than any other mine on the Mother Lode belt (Clark and Lydon, 1962). Large quantities of ore were mined, the maximum having been 245,000 tons in 1918, the next to last year of operation by this concern. The total value of gold produced by the Melones Consolidated Mining Company was about $4.5 million (Logan, 1935).

Meanwhile, in 1917, Carson Hills Gold Mines, Inc. was formed under the direction of W, J. Loring with A.D. Stevenot as mine superintendent. The old Morgan Mine was purchased in 1918. In 1919 they also acquired and consolidated the Calaveras Group, Melones, South Carolina, Iron Rock, Relief, Irvine, Rider, Adelaide, Stanislaus, and other claims. A new adit, known as the Morgan adit was driven in a southerly direction from the north side of the hill. A rich new ore body was encountered in schist in the hanging wall of the large massive "Bull" vein. This proved to be the upward extension of high-grade ore previously mined some 1300 feet below on the 1600-foot level (Knopf, 1929). In the next few years, this "Hanging Wall" ore body was mined to a depth of 4550 feet and yielded more than $5 million. Mill heads averaged over $20 per ton at times, but the average grade of the ores was $12.60/ton (Burgess, 1848). Additional properties were absorbed including those of the Melones Mining Company, and the name of the concern was changed to Carson Hill Gold Mining Company. A new 30-stamp mill was erected west of the 100-stamp mill. This concern operated the properties until 1926 when increasing costs and a decline in ore grade caused them to close the mine. The value of production for the 7 years of operation was $7 million (Clark and Lydon, 1962).

During these years, the Finnegan Mine was also being operated sporadically by a local family, prospecting the Finnegan and Melones veins and operating an old mill when sufficient ore was accumulated. In the mid-1920s, while working on the 1100-foot level, loose rock caused work to cease and shortly afterward the workings caved, creating a large landslide. In 1928, a 10-stamp mill was erected at the Finnegan Mine, but by the early 1930s, the Finnegan Mine was on its last legs with the only activity being dewatering of the workings.
In 1933, the Carson Hill Gold Mining Corporation was organized. The Morgan and Melones Mines were rehabilitated to the 3000-foot level where newly discovered ore bodies in the footwall area were exposed. These were mined from that depth to the surface. Operations were stimulated by the increase in the gold price to $35 an ounce in 1935, enabling the company to work downward to the 3500-foot level. It was during this time that the large pits were developed, including the Relief, the Union Shovel Pit (Morning Glory Hole), and the Footwall glory holes west and south of the Bull vein. The Calaveras Mine was also operated with mining on the upper levels. The capacity of the 30-stamp mill was increased to 20,000 tons per month. The peak year of production for this mill was 1939 when $937,156 worth of gold was sold. The Carson Hill Gold Mining Corporation continued operations until May 1942 when the mill burned to the ground. During this period of operation 2,400,000 tons of ore were mined which yielded a total of $6.5 million. Any hope of rebuilding the mill and resuming operations was crushed by the enactment of Government Order L-208 (Gold Mine Closing Order) in 1942 to help the war effort.

The properties of the Carson Hill Mines group lay idle until 1975 when they were acquired by Cyprus Mines Corporation. After the evaluation of the properties, Cyprus abandoned the project. In 1984, Grandview Resources acquired the property. Following further evaluations including 43,000 feet of reverses circulation drilling, the decision was made to proceed with mining. Permits to reopen the mine as an open-pit operation were approved in 1985. Operations consisted of open pit mining with extraction by heap leaching using a valley leach method, carbon in column adsorption, high temperature-low pressure glycol elution, and electrowinnowing. Ore was produced at rates that ranged from 7,000 to 14,000 tons per day (Collum, 1990) with an average gold content ranging from 0.046-0.057 oz./ton. Recovery averaged between 70% to 75%. The first doré bar was poured in December 1986. In 1988 Western Mining Corporation took over operations, but mining operations ceased in October 1989, after dropping gold prices and a deteriorating heap leach recovery rate made operation uneconomic. During this short period, the mine produced 90,000 ounces of gold (Collum, 1990). The mine site underwent reclamation during the 1990s.

The following is a brief summary of some of the principal early mines comprising the Carson Hill mines group (from Clark and Lydon, 1962):

Calaveras Mine

The Calaveras Mine, which was also known as the Calaveras Consolidated, originally consisted of several claims of which the Calaveras and Santa Cruz were the most important. The property is was on the southwest slope of Carson Hill west of the Melones Mine. Large-scale mining of low-grade ore bodies in the Carson Hill area began at the Calaveras Mine soon after 1889. The mine was a major source of ore during the later part of operations of the Carson Hill Mining Company (1918-1926). During the operations of the Carson Hill Mining Corporation (1933-1942), it was mined extensively both underground and in open cuts.

The mine was developed by the 1500-foot Calaveras adit, the portal of which was just west of State Highway 49 at Melones, several raises, and two open cuts on the adjacent northern slope, known as the north and south pits. These workings were on the Calaveras vein system.

Finnegan Mine

The Finnegan Mine was located on the northeast slope of Carson Hill between the Reserve and Boston Consolidated claims. The mine was operated separately from the other Carson Hill group mines for much of its history. The mine was discovered in 1856 by John Finnegan. In 1867, a small rich ore shoot which yielded $80,000 to $100,000 was encountered on the property. During the latter part of the 19th century, the mine was almost continuously active. In 1894, it was being worked on a small scale for pockets. In the early 1900s, it was worked chiefly by the open-pit method, and in 1910, a $10,000 pocket was discovered.

The open cuts of the Finnegan and the adjoining Reserve claim of the Melones Mining Company finally joined and a suit against the latter concern resulted. From about 1920 until about 1931, Lewis, Gilman, and Moore operated the mine.

The ore body consisted of mineralized amphibolite schist as much as 100 feet thick on the footwall of the Bull vein. This was developed by open cut. To the east, a narrow west-dipping quartz vein was developed by a 350-foot inclined shaft.

Melones Mine

The Melones mine consisted of eight claims consolidated by the Melones Mining Company in 1895 and operated as a unit until 1919. They extended from the summit of Carson Hill south to the river and are on and east of the Bull vein. All of the claims had earlier histories. The Melones Mine was best known for the large quantities of low-grade ore mined and milled at low cost. The main working entry was the Melones adit, which extended 500 feet from portal to workings.

Morgan Mine

Located on the northwest slope of Carson Hill, the Morgan Mine produced the largest amount of gold in the area. Discovered in 1850, it had yielded at least $2.8 million by the end of 1851. In 1854, a large mass of gold was found on the property. The mine was active during the 1860s. It was idle during much of the following period until 1918, when it was acquired by the Carson Hill Gold Mining Company. In driving the Morgan adit, the famous Hanging wall ore shoot was discovered, consequently, the Morgan and adjoining Melones mine were major sources of ore from 1920 to 1926. This mine was again highly productive during the operations of the Carson Hill Gold Mining Corporation (1933-1942). The principal working entries were the Morgan adit, the Morgan shaft, and the immense Morgan glory hole. The gold production from the district declined in the late 1850s. Large-scale mining of low-grade ore bodies began in 1889 at the Calaveras mine. The Melones mine was worked on a major scale from 1895 to 1918. The Morgan, Calaveras, and Melones mines were consolidated in 1918 and worked as a unit until 1926. They were operated again from 1933 until 1942. This was one of the richer portions of the Mother Lode, the Carson Hill group alone having yielded an estimated total of $26 million. Part of Carson Hill will be inundated by the New Melones Reservoir.

Geology: The district is underlain by a series of northwest-striking beds of phyllite, amphibolite, greenschist, and serpentine. The widespread hydrothermal alteration has changed much of the serpentine to extensive bodies of mariposite-ankerite-quartz rock. The slate of the Mariposa Formation (Upper Jurassic) lies to the west and metasediments of the Calaveras Formation (Carboniferous to Permian) to the east.

Ore deposits: The deposits consist of thick, massive, and often barren quartz veins, with adjacent large bodies of auriferous schist and pyritic ankerite mariposite-quartz rock containing numerous thin quartz seams and stringers. Milling ore usually was low in grade, but the ore bodies were extensive. The famous Hanging Wall orebody, which consisted of auriferous schist, averaged Yz ounce of gold per ton and had dimensions of 175 x 4500 x 15 feet. Much rich high-grade ore from surface pockets was recovered in the 1850s. Tellurides, which included calaverite, sylvanite, hessite, and petzite, were recovered in quantity during the early days, near the surface. Both calaverite and melonite, a rare nickel telluride, were first found and described from this district.

Mines: Carson Hill Mines ($26 million), Calaveras, Finnegan, Melones, Morgan, Reserve, Stanislaus Mines, Carson Creek ($1 million), Hardy, Santa Ana, Tulloch.

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