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Register of the Oenn Chemical Works (Campo Seco, Calif.) Assay Records, 1912-1919
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Collection Details
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  • Descriptive Summary
  • Administrative Information
  • Biography
  • Scope and Content

  • Descriptive Summary

    Title: Oenn Chemical Works (Campo Seco, Calif.) Assay Records,
    Date (inclusive): 1912-1919
    Collection number: Mss14
    Extent: 0.5 linear ft.
    Repository: University of the Pacific. Library. Holt-Atherton Department of Special Collections
    Stockton, CA 95211
    Shelf location: For current information on the location of these materials, please consult the library's online catalog.
    Language: English.

    Administrative Information


    Collection is open for research.

    Preferred Citation

    [Identification of item], Oenn Chemical Works (Campo Seco, Calif.) Assay Records, Mss14, Holt-Atherton Department of Special Collections, University of the Pacific Library


    Campo Seco, eight miles southwest of Mokelumne Hill in Calaveras County prospered briefly as a gold mining camp (1850-1860), but in later years was known principally for its production of copper and zinc, most notably from the Penn Mine. In 1887 the Penn Chemical Co. acquired a mining site and erected a smelter (1899) which served the Penn mines through 1919. The smelter was equipped with a crushing and grinding plant, eight roasting furnaces and a blast furnace. The smelter was shut down and dismantled when the price of copper declined following World War I. Gross returns from the smelting operation exceeded $7 million.

    Scope and Content

    This collection consists of pages of unbound printed forms on which daily assay samples are recorded, giving the percentages of copper, iron, etc. in each sample. Since the period covered by these records includes the World War I years, the data displayed may show an increase in mining activity in response to war needs.