Copperopolis property, California

The Copperopolis mine was a chrysotile mine near Copperopolis, in Calaveras County, California, worked in turn by Jefferson Lake, Pacific Asbestos and Calaveras Asbestos.^3,10,11,12 The earliest rows come from 1921, when Asbestos, the industry's trade journal, reported the claims of a stock offering by the Pacific Asbestos Corporation: holdings of "600 acres located in Calaveras County, California, 46 miles east of Stockton near Copperopolis along the Stanislaus River," deposits "reputed to be of the Chrysotile variety similar to Canadian in quality," and "8,000,000 tons of Asbestos bearing rock" blocked out, "estimated to contain 5.17% Asbestos fibre."¹ The money was to go toward "a mill with capacity of 1000 tons of rock every eight hour shift."¹ In June 1922 the trade journal reported that the corporation "has built a mill near Copperopolis," but that Calaveras County was "not yet actively producing."⁵

Jefferson Lake

The U.S. Bureau of Mines' Minerals Yearbook for 1958, drawing on the Wall Street Journal, reports that the Jefferson Lake Sulfur Co. "began a diamond-drilling campaign to explore the asbestos deposits of the American Asbestos Mining Corp. in Calaveras County."¹³ In March 1959 the trade journal reported an agreement under which Jefferson Lake "has been granted the right to explore and develop" the property, with reports "very favorable" for "a deposit of excellent asbestos fibre of the chrysotile variety."² The yearbook for 1959 says Jefferson Lake "purchased the Copperopolis, Calif., property of American Asbestos Mining Corp. after a diamond-drilling program had outlined 15 million tons of ore," and "announced plans to erect a mill to process 2,000 tons of ore per day."³

Not every source was so sure. In May 1960 a writer in Asbestos who had studied the deposits during the war said that a local newspaper put "the purchase price" at "$4,620,000 for about 500 acres," that the owners "have drilled a reported 55 diamond drill holes," and that "the tonnage figure given out is 15,000,000 tons proven, which vastly exceeds any earlier tonnage estimates known to the writer."⁴ Elsewhere on the property, the writer said, the fiber showed "none with any persistence," at least as drilled in the war years.⁴ Jefferson Lake's own report for 1960 described its subsidiary's "major asset" as "a 480-acre asbestos-bearing tract near Copperopolis."¹⁴

The yearbook reports that in 1960 Jefferson Lake "acquired ground for a mill site and tailing disposal," and that in 1961 its subsidiary, Jefferson Lake Asbestos Corp., "completed exploration and clearing of its chrysotile deposit near Copperopolis," and began building "a $5 million mill with a planned initial annual capacity of 15,000 tons of fiber."^6,7 The yearbook for 1962 gives a different figure: the new plant "went into production late in 1962 with capacity rated at 70,000 tons of fiber annually," and "several shipments went to Japan."⁸ For 1963 the yearbook called Jefferson Lake Asbestos Corp. the "second largest producer."¹⁵

Pacific Asbestos

By 1964 the yearbook listed the company as "Pacific Asbestos Corp. (formerly Jefferson Lake Asbestos Corp.)," and a 1964 report summed up in Asbestos said it "resumed full scale operations late in the year at its mine and processing plant near Copperopolis."^10,16 The yearbook notes that Pacific Asbestos, by then "the largest producer" in California, was "acquired by H. K. Porter Co. Inc. during 1968."^17,18 The yearbooks for 1971, 1972 and 1973 say the growth of California's asbestos output "was led by" Pacific Asbestos Corp.'s mine in Calaveras County, and for 1973 that the Vermont mine of GAF Corp. had the highest production but "was surpassed by Pacific Asbestos in product value."^19,20,21

The sources differ on when the mine closed in 1974: the Minerals Yearbook for 1974 marks the mine "closed at yearend."⁹ Asbestos reported in 1975 that H. K. Porter, which "had owned a 92.5% interest in the former Pacific Asbestos Corporation," had "permanently closed the mine and plant in April 1974."²² At the end of 1974, the yearbook says, "negotiation was underway aimed at acquisition and reopening of the Pacific Asbestos mine."⁹

Calaveras Asbestos

A group of American and German investors bought the mine and mill from H. K. Porter; the acquisition "became final October 24, 1975," and the new company was Calaveras Asbestos Ltd.^11,22,23 The trade journal reported that "the installation of necessary environmental equipment has already begun," and the yearbook that the group "fully expects to operate profitably under full compliance."^11,22 Production was scheduled for early 1976; the trade journal expected it "by March 1, 1976."^11,22 The yearbook for 1976 reports "the newly reopened Calaveras (Pacific) mine," and that "by yearend, Calaveras Asbestos Corp. was in full operation"; its management said "the firm was profitable after 1 year of operation."²⁴ The trade journal wrote that the company produced "Chrysotile Grades 4-7," mostly "used in the manufacture of asbestos-cement pipes and sheets," and California Geology, as the journal quoted it, said the serpentine was "mined in open pits."^25,26,27

For 1977 the yearbook names Calaveras Asbestos "California's leading producer," and for 1978 through 1984 "California's and the Nation's leading producer" from its Copperopolis mine.^{12,28,29,30,31,32,33} For 1985 it calls the company "the leading U.S. producer of asbestos," and for 1986 says it "led in asbestos sales in the United States."^34,35 A 1981 equipment maker's feature in Asbestos gave "annual 40,000 tons of processed asbestos" and "a 565-acre site in the Sierra Nevada foothills," and described the company's plan "to double the three-million-tons-per-year excavation pace," with an "overall stripping ratio" of "slightly over 2.2:1."³⁶

The company's president, Gordon A. Coats, told the trade journal in 1978 of energy costs up "over 100% increase in one year" and "environmentally-related expenses (400% over budget)," and that Wilbur-Ellis/Connell Bros., which had represented the company for two years, "has now acquired an interest."²⁷ In 1980 the company wrote that "our mine was impacted particularly hard due to the enactment of the Federal Mine Safety Act," and that a program to "move substantial quantities of waste rock" would "extend the mine life by several years," with new ore reserves expected "by 1982."³⁷ The trade journal said in 1981 that the waste rock program had been underway "since the final quarter of 1979" and that "new ore reserves should be reached by March 1982."³⁸

The closing

The Minerals Yearbook for 1987, drawing on the Stockton Record, reports that "Calaveras Asbestos permanently closed its mine in Copperopolis, CA, on December 31, 1987," and that the company, "the largest of the three domestic asbestos producers, cited depleted ore reserves and decreased market demand as the reason for closing."³⁹ The same report says that "plans were made to open the mine in 1988 as a disposal site for asbestos-containing materials under a new company name, Cal-Safe."³⁹

The documents report this mine producing asbestos fiber for sale.⁸

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Location

Output the documents report

Figures as printed, in the units each document uses (short tons before about 1990, metric tons after, in most U.S. chapters). Some are a year's output, some a daily rate or a capacity, some a company's total rather than this mine's alone; the statement for that year below says which.

Year	Figure	Source
1981	40,000 tons of processed asbestos (annual)	36

Year by year

Every statement about this mine in the documents, in each document's own words, by the year it is about.

1921

• Ownership: “The holdings of the corporation cover 600 acres” (Pacific Asbestos Corporation), said by Pacific Asbestos Corporation, as reported by Asbestos (magazine), p. 60¹
• Mill: “construction of a mill with capacity of 1000 tons of rock every eight hour shift” (Pacific Asbestos Corporation), said by Pacific Asbestos Corporation, as reported by Asbestos (magazine), p. 60¹
• Reserves: “8,000,000 tons of Asbestos bearing rock ... 5.17% Asbestos fibre” (Pacific Asbestos Corporation), said by Pacific Asbestos Corporation, as reported by Asbestos (magazine), p. 60¹
• Fiber: “reputed to be of the Chrysotile variety” (Pacific Asbestos Corporation), said by Pacific Asbestos Corporation, as reported by Asbestos (magazine), p. 60¹

1922

• Mill: “the Pacific Asbestos Corporation has built a mill near Copperopolis” (Pacific Asbestos Corporation), p. 35⁵
• Idle: “not yet actively producing” (Pacific Asbestos Corporation), p. 35⁵

1958

• Exploration: “began a diamond-drilling campaign to explore the asbestos deposits of the American Asbestos Mining Corp.” (Jefferson Lake Sulfur Co.), as reported by Wall Street Journal, p. 2¹³

1959

• Ownership: “Jefferson Lake has been granted the right to explore and develop the asbestos mining property situated in Calaveras County, California, owned by American Asbestos” (Jefferson Lake Sulphur Company; American Asbestos Mining Corporation), p. 39²
• Exploration: “Further diamond drilling will begin within thirty days in order to confirm the extent of the deposit” (Jefferson Lake Sulphur Company), p. 39²
• Fiber: “a deposit of excellent asbestos fibre of the chrysotile variety” (Jefferson Lake Sulphur Company), p. 39²
• Reserves: “a diamond-drilling program had outlined 15 million tons of ore” (Jefferson Lake Sulphur Co.), p. 2³
• Ownership: “purchased the Copperopolis, Calif., property of American Asbestos Mining Corp.” (Jefferson Lake Sulphur Co.), p. 2³
• Mill: “The firm announced plans to erect a mill to process 2,000 tons of ore per day” (Jefferson Lake Sulphur Co.), p. 2³
• Exploration: “have drilled a reported 55 diamond drill holes averaging 200' to 250' deep, with the deepest 600'”, p. 6⁴
• Ownership: “a local newpaper item dated December 4, 1959, says the purchase price was $4,620,000 for about 500 acres”, p. 6⁴

1960

• Fiber: “pockets and lenses of fiber, many showing good, Canadian-type, cross-fiber chrysotile”, p. 6⁴
• Reserves: “The tonnage figure given out is 15,000,000 tons proven, which vastly exceeds any earlier tonnage estimates known to the writer”, p. 6⁴
• Mill: “acquired ground for a mill site and tailing disposal contiguous to its asbestos deposit near Copperopolis” (Jefferson Lake Sulphur Co.), p. 2⁶
• Ownership: “the Jefferson Lake Asbestos Corporation. This subsidiary's major asset is a 480-acre asbestos-bearing tract near Copperopolis” (Jefferson Lake Asbestos Corporation), said by Jefferson Lake Sulphur Company, as reported by Asbestos (magazine), p. 44¹⁴

1961

• Exploration: “completed exploration and clearing of its chrysotile deposit near Copperopolis ... in preparation for mining” (Jefferson Lake Asbestos Corp.), p. 2⁷
• Mill: “Construction was begun on a $5 million mill with a planned initial annual capacity of 15,000 tons of fiber” (Jefferson Lake Asbestos Corp.), p. 2⁷
• Fiber: “chrysotile deposit” (Jefferson Lake Asbestos Corp.), p. 2⁷
• Ownership: “Jefferson Lake Asbestos Corp., a subsidiary of Jefferson Lake Sulphur Co.” (Jefferson Lake Asbestos Corp.), p. 2⁷

1962

• Mill: “capacity rated at 70,000 tons of fiber annually” (Jefferson Lake Asbestos Co.), p. 2⁸
• Worked: “reported production and shipments: Jefferson Lake Asbestos Corp., Calaveras County” (Jefferson Lake Asbestos Corp.), p. 2⁸
• Buyers: “Several shipments went to Japan” (Jefferson Lake Asbestos Co.), p. 2⁸
• Opened: “went into production late in 1962” (Jefferson Lake Asbestos Co.), p. 2⁸

1963

• Worked: “Production and shipments were reported by ... Jefferson Lake Asbestos Corp., Calaveras County” (Jefferson Lake Asbestos Corp.), p. 2¹⁵
• Output: “Second largest producer was Jefferson Lake Asbestos Corp., Calaveras County, Calif.” (Jefferson Lake Asbestos Corp.), p. 2¹⁵

1964

• Worked: “Pacific Asbestos Corp. (formerly Jefferson Lake Asbestos Corp.), Calaveras County” (Pacific Asbestos Corp.), p. 2¹⁰
• Ownership: “Pacific Asbestos Corp. (formerly Jefferson Lake Asbestos Corp.)” (Pacific Asbestos Corp.), p. 2¹⁰
• Fiber: “chrysotile” (Pacific Asbestos Corp.), p. 2¹⁰
• Worked: “resumed full scale operations late in the year at its mine and processing plant near Copperopolis” (Pacific Asbestos Corporation), as reported by Asbestos (magazine), p. 23¹⁶

1965

• Worked: “Pacific Asbestos Corp. from the Pacific Asbestos mine, Calaveras County” (Pacific Asbestos Corp.), p. 2⁴⁰

1968

• Ownership: “Acquired by H. K. Porter Co. Inc. during 1968” (H. K. Porter Co. Inc.), p. 2¹⁷
• Worked: “Pacific Asbestos Corp 1 | Calaveras | Pacific Asbestos | Do.” (Pacific Asbestos Corp), p. 2¹⁷
• Fiber: “prepared and shipped fibers that fall within Groups 4 through 7” (Pacific Asbestos Corporation), as reported by Asbestos (magazine), p. 37¹⁸

1969

• Worked: “Pacific Asbestos Corp. | Calaveras | Pacific Asbestos | Do.” (Pacific Asbestos Corp.), p. 3⁴¹

1970

• Worked: “Pacific Asbestos Corp. | Calaveras | Pacific Asbestos | Do.” (Pacific Asbestos Corp.), p. 2⁴²

1971

• Worked: “Pacific Asbestos Corp. | Calaveras | Pacific Asbestos | Do.” (Pacific Asbestos Corp.), p. 2¹⁹
• Output: “The 10 percent increase in production to 87,144 tons was led by Pacific Asbestos Corp.'s mine in Calaveras County” (Pacific Asbestos Corp.), p. 2¹⁹
• Output: “The 10% increase was led by Pacific Asbestos Corporation's mine in Calaveras County” (Pacific Asbestos Corporation), as reported by Asbestos (magazine), p. 40⁴³

1972

• Output: “was led by the Pacific Asbestos Corp. mine in Calaveras County” (Pacific Asbestos Corp.), p. 2²⁰
• Worked: “Pacific Asbestos Corp. | Calaveras | Pacific Asbestos | Do.” (Pacific Asbestos Corp.), p. 2²⁰

1973

• Output: “was led by Pacific Asbestos Corp.'s mine in Calaveras County” (Pacific Asbestos Corp.), p. 2²¹
• Worked: “Pacific Asbestos Corp. | Calaveras | Pacific Asbestos | Do.” (Pacific Asbestos Corp.), p. 3²¹
• Output: “surpassed by Pacific Asbestos in product value” (Pacific Asbestos Corp.), p. 3²¹

1974

• Worked: “Pacific Asbestos Corp 1 | Calaveras | Pacific Asbestos | Do.” (Pacific Asbestos Corp.), p. 2⁹
• Closed: “Pacific Asbestos Corp 1 ... 1 Closed at yearend.” (Pacific Asbestos Corp.), p. 2⁹
• Closed: “followed by the closing of the Pacific Asbestos Corp. mine” (Pacific Asbestos Corp.), p. 2⁹
• Ownership: “negotiation was underway aimed at acquisition and reopening of the Pacific Asbestos mine” (Pacific Asbestos Corp.), p. 2⁹
• Dust and health: “at least somewhat of a factor in the closing of two mines in California”, p. 2⁹
• Closed: “that of the Pacific Asbestos Corp. mine” (Pacific Asbestos Corp.), p. 2¹¹
• Closed: “mine closed in 1974 by H. K. Porter Co., Inc.” (H. K. Porter Co., Inc.), p. 2¹¹
• Closed: “had permanently closed the mine and plant in April 1974” (H. K. Porter Company, Inc.), p. 20²²

1975

• Ownership: “A group of West German and American investors bought and is refurbishing the Copperopolis, Calif., mine” (Calaveras Asbestos Ltd.), p. 2¹¹
• Dust and health: “fully expects to operate profitably under full compliance” (Calaveras Asbestos Ltd.), p. 2¹¹
• Idle: “Closed during 1975; due to open early 1976.” (Calaveras Asbestos Ltd.), p. 3¹¹
• Ownership: “By yearend Calaveras Asbestos Ltd. was successful in the acquisition of the Pacific Asbestos mine” (Calaveras Asbestos Ltd.), p. 2¹¹
• Worked: “Calaveras Asbestos Ltd. 1 | Calaveras | Copperopolis | Do.” (Calaveras Asbestos Ltd.), p. 3¹¹
• Ownership: “A group of American and German investors have purchased the Chrysotile asbestos mine and mill, located at Copperopolis, California, from H. K. Porter Company, Inc.” (Calaveras Asbestos Ltd. (CAL); Calaveras Natural Resources (CNR)), p. 38²³
• Ownership: “purchase by a group of U.S. and German investors from H. K. Porter Company, Inc., of the Chrysotile asbestos mine and mill at Copperopolis; The acquisition became final October 24, 1975” (Calaveras Asbestos Ltd.), p. 20²²

1976

• Opened: “Production was scheduled to begin early in 1976” (Calaveras Asbestos Ltd.), p. 2¹¹
• Worked: “is producing Chrysotile Grades 4-7 at its mining/milling operation at Copperopolis” (Calaveras Asbestos Ltd.), p. 27²⁵
• Worked: “By yearend, Calaveras Asbestos Corp. was in full operation” (Calaveras Asbestos Corp.), p. 2²⁴
• Worked: “Calaveras Asbestos Corp | Calaveras | Copperopolis | Do. [chrysotile]” (Calaveras Asbestos Corp), p. 3²⁴
• Opened: “the newly reopened Calaveras (Pacific) mine”, p. 1²⁴
• Fiber: “chrysotile” (Calaveras Asbestos Corp), p. 3²⁴
• Ownership: “Calaveras Asbestos Corp. mine (formerly Pacific Asbestos Corp.)” (Calaveras Asbestos Corp.), p. 2²⁴
• Opened: “Reopening of the Calaveras Asbestos Corp. mine (formerly Pacific Asbestos Corp.)” (Calaveras Asbestos Corp.), p. 2²⁴
• Description: “the firm was profitable after 1 year of operation” (Calaveras Asbestos Corp.), p. 2²⁴
• Opened: “Production is expected to commence by March 1, 1976” (Calaveras Asbestos Ltd.), p. 20²²

1977

• Worked: “Calaveras Asbestos Ltd., Copperopolis, mines Grades 4-7 Chrysotile” (Calaveras Asbestos Ltd.), p. 22²⁶
• Output: “Output from the copperopolis mine made Calaveras Asbestos Corp. California's leading producer” (Calaveras Asbestos Corp.), p. 2²⁸
• Worked: “Calaveras Asbestos Corp | Calaveras | Copperopolis | Do. [chrysotile]” (Calaveras Asbestos Corp), p. 2²⁸
• Fiber: “chrysotile” (Calaveras Asbestos Corp), p. 2²⁸

1978

• Description: “In both areas Chrysotile asbestos-bearing serpentine is mined in open pits” (Calaveras Asbestos Ltd.), as reported by California Geology, p. 20²⁷
• Ownership: “Wilbur-Ellis/Connell Bros., an organization which had represented Calaveras Asbestos for two years, has now acquired an interest in the company” (Wilbur-Ellis/Connell Bros.), p. 20²⁷
• Output: “California's and the Nation's leading producer from its Copperopolis mine” (Calaveras Asbestos Corp.), p. 3²⁹
• Fiber: “chrysotile” (Calaveras Asbestos Corp), p. 4²⁹
• Worked: “Calaveras Asbestos Corp | Calaveras | Copperopolis | Do. [chrysotile]” (Calaveras Asbestos Corp), p. 4²⁹

1979

• Dust and health: “Our mine was impacted particularly hard due to the enactment of the Federal Mine Safety Act” (Calaveras Asbestos Ltd.), said by Calaveras Asbestos Ltd., p. 8³⁷
• Exploration: “to move substantial quantities of waste rock so as to extend the mine life by several years; we expect to open new ore reserves by 1982” (Calaveras Asbestos Ltd.), said by Calaveras Asbestos Ltd., p. 8³⁷
• Exploration: “An ambitious waste rock removal program has been underway at the Calaveras open-pit operation since the final quarter of 1979 to expand the mine. New ore reserves should be reached by March 1982” (Calaveras Asbestos Ltd.), p. 13³⁸

1980

• Worked: “California: Calaveras Asbestos Corp | Calaveras | Copperopolis | Do. [chrysotile]” (Calaveras Asbestos Corp), p. 3³⁰
• Fiber: “chrysotile” (Calaveras Asbestos Corp), p. 3³⁰
• Output: “California's and the Nation's leading producer from its Copperopolis Mine” (Calaveras Asbestos Corp.), p. 3³⁰

1981

• Description: “to double the three-million-tons-per-year excavation pace; Overall stripping ratio averages slightly over 2.2:1” (Calaveras Asbestos Ltd.), p. 6³⁶
• Output: “Calaveras Asbestos is the largest asbestos producer in the United States. Most of its annual 40,000 tons of processed asbestos is consumed in asbestos-cement products” (Calaveras Asbestos Ltd.), p. 6³⁶
• Output: “California's and the Nation's leading producer from its Copperopolis Mine” (Calaveras Asbestos Corp.), p. 3³¹
• Fiber: “chrysotile” (Calaveras Asbestos Corp), p. 3³¹
• Worked: “California: Calaveras Asbestos Corp | Calaveras | Copperopolis | Do. [chrysotile]” (Calaveras Asbestos Corp), p. 3³¹

1982

• Worked: “California: Calaveras Asbestos Corp | Calaveras | Copperopolis | Chrysotile.” (Calaveras Asbestos Corp), p. 3¹²
• Output: “California's and the Nation's leading producer, from its Copperopolis Mine” (Calaveras Asbestos Corp.), p. 2¹²
• Fiber: “chrysotile” (Calaveras Asbestos Corp), p. 3¹²

1983

• Output: “California's and the Nation's leading producer, from its Copperopolis Mine” (Calaveras Asbestos Corp.), p. 2³²
• Fiber: “chrysotile” (Calaveras Asbestos Corp), p. 2³²
• Worked: “California: Calaveras Asbestos Corp | Calaveras | Copperopolis | Chrysotile.” (Calaveras Asbestos Corp), p. 2³²

1984

• Output: “California's and the Nation's leading producer, from its Copperopolis Mine” (Calaveras Asbestos Corp.), p. 2³³
• Worked: “California: Calaveras Asbestos Corp | Calaveras | Copperopolis | Chrysotile.” (Calaveras Asbestos Corp), p. 3³³
• Fiber: “chrysotile” (Calaveras Asbestos Corp), p. 3³³

1985

• Worked: “California: Calaveras Asbestos Ltd | Calaveras | Copperopolis | Chrysotile.” (Calaveras Asbestos Ltd), p. 2³⁴
• Output: “Calaveras Asbestos Ltd. in California was the leading U.S. producer of asbestos” (Calaveras Asbestos Ltd.), p. 2³⁴
• Fiber: “chrysotile” (Calaveras Asbestos Ltd), p. 2³⁴

1986

• Fiber: “chrysotile” (Calaveras Asbestos Ltd), p. 3³⁵
• Output: “Calaveras Asbestos Ltd. in California led in asbestos sales in the United States” (Calaveras Asbestos Ltd.), p. 2³⁵
• Worked: “California: Calaveras Asbestos Ltd | Calaveras | Copperopolis | Chrysotile.” (Calaveras Asbestos Ltd), p. 3³⁵

1987

• Output: “the largest of the three domestic asbestos producers” (Calaveras Asbestos Ltd.), as reported by Stockton Record, p. 2³⁹
• Reserves: “cited depleted ore reserves” (Calaveras Asbestos Ltd.), as reported by Stockton Record, p. 2³⁹
• Worked: “Calaveras Asbestos Ltd., Calaveras County, CA” (Calaveras Asbestos Ltd.), p. 2³⁹
• Closed: “the closing of Calaveras Asbestos Corp. in 1987” (Calaveras Asbestos Corp.), p. 2⁴⁴
• Closed: “permanently closed its mine in Copperopolis, CA, on December 31, 1987” (Calaveras Asbestos Ltd.), as reported by Stockton Record, p. 2³⁹

1988

• Description: “open the mine in 1988 as a disposal site for asbestos-containing materials” (Cal-Safe), as reported by Stockton Record, p. 2³⁹

In court opinions

Court opinions in our case-law library that name this mine, by how they concern it. A search found every one that names the mine and an AI reader sorted them; the quotation, checked word for word against the text, shows where. Those that name the mine only in passing or in a reference list are left out.

The mine’s fiber in products (3)

• Noll v. American Biltrite Inc. (2017): “Special Electric had a nationwide sales presence in the United States as the exclusive sales agent for two asbestos mining companies, "General Mining and Finance and [the] Calaveras Asbestos Company."”
• Trapp v. CertainTEED Corporation (2018): “Calaveras was also one of multiple asbestos suppliers to CertainTeed between 1976 through 1982.”
• Union Carbide Corporation v. Fields (2012): “U. S. Gypsum's interrogatory response, which identifies, among other companies, Asbestos Corp., Atlas, Johnson Mines, Nicolet, and Pacific Asbestos as companies known to have been approved suppliers of asbestos to U. S. Gypsum.”

In medical studies

Medical studies in our research library that name this mine, by how they concern it. A search found every one that names the mine and an AI reader sorted them; the quotation, checked word for word against the text, shows where. Those that name the mine only in passing or in a reference list are left out.

Studies of the mine’s fiber (1)

• McCrone WC 1974: Detection and identification of asbestos by microscopical dispersion staining

Other names

Documents call this mine “asbestos deposits of the American Asbestos Mining Corp.”, “Copperopolis, Calif., property of American Asbestos Mining Corp.”, “chrysotile deposit near Copperopolis”, “new plant of Jefferson Lake Asbestos Co., located near Copperopolis”, “Pacific Asbestos mine”, “Pacific Asbestos”, “Copperopolis”, “Copperopolis Mine”, “copperopolis mine”, “Calaveras (Pacific) mine”, “Calaveras Asbestos Corp. mine”, “Calaveras Asbestos Ltd.”, “Calaveras Asbestos Corp.”, “Calaveras Asbestos”, “Pacific Asbestos Corporation holdings”, “Pacific Asbestos Corporation mine”, “Calaveras Asbestos Ltd. mine”.

See also

• Pacific Asbestos Corp.: the company's history, documents, people, products and plants
• H. K. Porter Co. Inc.: the company's history, documents, people, products and plants
• Calaveras Asbestos Ltd.: the company's documents, people, products and plants
• Asbestos exposure sites in California
• All asbestos mines

References

1. Asbestos Magazine, 1921, September 1921 (September 1, 1921), p. 60.
2. Asbestos Magazine, 1959, March 1959 (March 1, 1959), p. 39.
3. Minerals Yearbook: Asbestos Chapters, 1959 (January 1, 1960), p. 2.
4. Asbestos Magazine, 1960, May 1960 (May 1, 1960), p. 6.
5. Asbestos Magazine, 1922, June 1922 (June 1, 1922), p. 35.
6. Minerals Yearbook: Asbestos Chapters, 1960 (January 1, 1961), p. 2.
7. Minerals Yearbook: Asbestos Chapters, 1961 (January 1, 1962), p. 2.
8. Minerals Yearbook: Asbestos Chapters, 1962 (January 1, 1963), p. 2.
9. Minerals Yearbook: Asbestos Chapters, 1974 (January 1, 1975), p. 2.
10. Minerals Yearbook: Asbestos Chapters, 1964 (January 1, 1965), p. 2.
11. Minerals Yearbook: Asbestos Chapters, 1975 (January 1, 1976), pp. 2–3.
12. Minerals Yearbook: Asbestos Chapters, 1982 (January 1, 1983), pp. 2–3.
13. Minerals Yearbook: Asbestos Chapters, 1958 (January 1, 1959), p. 2.
14. Asbestos Magazine, 1961, May 1961 (May 1, 1961), p. 44.
15. Minerals Yearbook: Asbestos Chapters, 1963 (January 1, 1964), p. 2.
16. Asbestos Magazine, 1966, June 1966 (June 1, 1966), p. 23.
17. Minerals Yearbook: Asbestos Chapters, 1968 (January 1, 1969), p. 2.
18. Asbestos Magazine, 1970, April 1970 (April 1, 1970), p. 37.
19. Minerals Yearbook: Asbestos Chapters, 1971 (January 1, 1972), p. 2.
20. Minerals Yearbook: Asbestos Chapters, 1972 (January 1, 1973), p. 2.
21. Minerals Yearbook: Asbestos Chapters, 1973 (January 1, 1974), pp. 2–3.
22. Asbestos Magazine, 1975, December 1975 (December 1, 1975), p. 20.
23. Asbestos Magazine, 1975, November 1975 (November 1, 1975), p. 38.
24. Minerals Yearbook: Asbestos Chapters, 1976 (January 1, 1977), pp. 1–3.
25. Asbestos Magazine, 1976, December 1976 (December 1, 1976), p. 27.
26. Asbestos Magazine, 1977, December 1977 (December 1, 1977), p. 22.
27. Asbestos Magazine, 1978, December 1978 (December 1, 1978), p. 20.
28. Minerals Yearbook: Asbestos Chapters, 1977 (January 1, 1978), p. 2.
29. Minerals Yearbook: Asbestos Chapters, 1978–79 (January 1, 1980), pp. 3–4.
30. Minerals Yearbook: Asbestos Chapters, 1980 (January 1, 1981), p. 3.
31. Minerals Yearbook: Asbestos Chapters, 1981 (January 1, 1982), p. 3.
32. Minerals Yearbook: Asbestos Chapters, 1983 (January 1, 1984), p. 2.
33. Minerals Yearbook: Asbestos Chapters, 1984 (January 1, 1985), pp. 2–3.
34. Minerals Yearbook: Asbestos Chapters, 1985 (January 1, 1986), p. 2.
35. Minerals Yearbook: Asbestos Chapters, 1986 (January 1, 1987), pp. 2–3.
36. Asbestos Magazine, 1981, February 1981 (February 1, 1981), p. 6.
37. Asbestos Magazine, 1980, February 1980 (February 1, 1980), p. 8.
38. Asbestos Magazine, 1981, January 1981 (January 1, 1981), p. 13.
39. Minerals Yearbook: Asbestos Chapters, 1987 (January 1, 1988), p. 2.
40. Minerals Yearbook: Asbestos Chapters, 1965 (January 1, 1966), p. 2.
41. Minerals Yearbook: Asbestos Chapters, 1969 (January 1, 1970), p. 3.
42. Minerals Yearbook: Asbestos Chapters, 1970 (January 1, 1971), p. 2.
43. Asbestos Magazine, 1973, January 1973 (January 1, 1973), p. 40.
44. Minerals Yearbook: Asbestos Chapters, 1988 (January 1, 1989), p. 2.