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The Mineral Industry of California (as of 1947)

Excerpts from

Annual Report, Division of Mines for the Ninety-Eighth Fiscal Year,
July 1, 1946 to June 30, 1947

By Olaf P. Jenkins, Chief, California State Division of Mines.

Manuscript submitted for publication December 1947,
California State Division of Mines, California Journal of Mines and Geology,
pp. Vol. 43, No. 4, October 1947, pp. 389-412.Used with permission,
California Department of Conservation, California Geological Survey.

The Mineral Industry of California in 1947 (Compilation by Charles V. Averill, Supervising Mining Engineer, and Olaf P. Jenkins, Chief, California State Division of Mines. Manuscript submitted for publication July 29, 1947.)

Significance of the Mineral Industry of California

"In Table 3,* California stands third among the states of the Union for mineral output in 1945. In 1946 the value of mineral production in California was larger than that of any preceding year, with a record production both in amount and value reported for gypsum, lead, limestone, pumice, and volcanic ash, talc and soapstone, soda (soda ash and salt cake), salt, silica (quartz and glass sand), barite, calcium chloride, iodine, lithium minerals, potash, and serpentine. All-time records in total values were recorded for petroleum and natural gas although in 1945 the quantity produced was greater. The value of borates also reached anew high and 1946 tonnage was exceeded only in 1937. The 1946 production of cement and miscellaneous stone was exceeded in quantity and value only by that of 1942...."

(* Please note: Table 3 will not be presented in this document.)


"The recent accelerated shift to California of both population and industry has caused an intensified building boom in this sate, accompanied by a tremendous demand for the materials used in construction. Raw products necessary to make the structual materials include minerals and rocks; the critical shortage of lumber is causing substitution by mineral products. The cement mills of California are running near capacity, and the state is now leading all others in production of this ingredient of concrete. This means that the production of crushed rock, sand, and gravel necessary for aggregate is also at a high level. Other mineral raw materials that are in high demand for building are clay for brick and tile, gypsum for plaster and wall-board, and pumice for light-weight aggregate in concrete and building blocks. The artificial pumice known as perlite, for which volcanic glass is the raw material, will probably soon be produced in quantity.

"Among the mineral raw materials demanded in large quantities by the expanding industries of California is limestone, which is used in flux in smelting metals, in agriculture, in mortar, plaster, glass, fruit-sprays, water-purification, sugar-refining, manufacture of paper, and in many smaller industries...."

Building Stone (in California as of 1946/1947)

"Immense reserves and a large variety of building stones occur in California. granite, marble, sandstone, slate, diorite, granodiorite, and numerous volcanic rocks, including tuff, have been quarried in the state in large amounts for buildings and monuments. Years ago, dimension stone was used in buildings to the amount of roughly $1,000,000 annually, but this use has been largely displaced by concrete construction. Most of the granite now quarried is used for monuments and comes from Fresno, Lassen, Placer, San Bernardino, and San Diego Counties. Small amounts of marble are produced in San Luis Obispo and San Bernardino Counties. Large reserve of this stone still exist in many other counties. Sandstone and various types of volcanic rocks that break into flat slabs are in considerable demand for flagstone, garden construction, and decorative veneers on the fronts of buildings. Many such stones have a distinctive color, which adds to the value. Such stone is produced in Napa, Monterey, and Santa Barbara Counties."

Lime and Limestone (in California as of 1946/1947)

"In 1946, production of limestone in California broke all records. It is continuing at a high level in 1947. Deposits that are equipped for production are being operated at practically full capacity, and additional deposits are being equipped.

"Limestone or dolomite occur in all but a few of the counties in California, but only about 10 counties are important producers. The complexity of the geologic structure of the state, together with the discontinuity and local variation of the magnesia-lime ratio, cause many problems in both exploration and operation. In the Sierra Nevada, the limestones from Calaveras County to the south are likely to contain considerable magnesia. From Amador County to the north, the limestone is largely of the high-calcium variety. Recent sampling in Tuolumne County gave the following results from adjacent beds: for a width of 600 feet the limestone is high in calcium; for a width of 300 feet, 35.46 percent magnesium carbonate, 60.77 percent calcium carbonate. In four counties of the state, oyster shells are utilized as a substitute for limestone in poultry feeds and fertilizer, and for burning to lime. At the south end of San Francisco Bay, oyster shells dredged from the bay are used in the manufacture of portland cement. San Bernardino County and the Coast Range counties south of San Francisco are large producers of both limestone and dolomite. Shasta County is very abundantely (sic) supplied with limestone of three different geologic ages, but little is being done with it in 1947, although formerly large tonnages were used as flux at copper smelters.

"Lime, which is made by heating limestone to drive off the carbon dioxide, is one of the most important industrial chemicals. Raw limestone also has many industrial uses, of which an example is flux in smelting ores for recovery of metals. Finely pulverized limestone is added to soils to reduce acidity, to supply calcium as plant food, and to improve certain soils in other ways. The largest tonnages of limestone go into the manufacture of portland cement, considered separately in this report, under the heading Cement.* Small amounts of marble, a variety of limestone, are still used in the building industry, and this has been mentioned under the heading Building stone. In California, only small amounts of limestone are used as crushed rock in aggregate for concrete and in building roads. In a few industries such as the manufacture of soda-ash and the production of beet-sugar, both the lime and the carbon dioxide driven from the limestone to make lime are utilized in the process.

(* Please note: The section on "Cement" will not be presented in this document.)

"Lime is used in the open-hearth steel industry, in brick mortar, plaster, glass, stucco, fruit-sprays, water-purification, sugar-refining, manufacture of paper, and in many smaller industries. Dolomite lime, which is made by heating dolomite, the double carbonate of calcium and magnesium, is mentioned under the heading of magnesium salts. Much dolomite is used at open-hearth steel furnaces also."

Stone, Miscellaneous (in California as of 1946/1947)

"Stone for road surfacing and concrete aggregate has been produced in every county in California; such material has a wide variety of other uses. Great irregular chunks of 10 tons each, known as riprap, are dumped from barges into shallow parts of bays to form the sea-walls behind which sand and mud are pumped to reclaim the land; but in some of the metropolitan districts satisfactory and abundant riprap cannot be found near at hand. Small sizes of rock are used for railroad ballast, and the accompanying finely divided material is used in concrete and plasters. Certain types of sand are mined especially for making molds in foundries.

"Many different types of stone are used; also there are many ways of producing them. The 10-ton chunks of riprap are blasted from solid bodies of basalt and granite. One of the largest granite quarries is located near the San Andreas fault, where the faulting has crushed the granite to the extent that the amount of explosives needed is much lower than average. In Butte and Sacramento Counties, crushed rock is produced form old dredge-tailing; thus the waste from the gold-dredging industry becomes the valuable raw material of the crushed-rock industry. A favorite method of producing sand and gravel is to excavate the bars along streams with various types of dragline excavators. The pits thus formed are sometimes refilled by winter floods. Nature has had a part in improving the quality of this material; soft decomposed rocks have been pounded and pulverized and washed away as mud; the harder, more resistant rocks remain. In some plants the sand and gravel are washed and separated into various sizes by screens only; but most plants contain crushers to reduce the size of the cobbles and boulders.

"Concrete highways, dams, aqueducts, and canals require great quantities of sand, gravel, and crushed rock for aggregate. As long as this type of construction continues at a high level, the stone industry will continue to flourish. Smaller quantities of such material go into foundations, walls, and floors of buildings.

"Limestone is higher in value in most California deposits than other stones for various industrial and chemical uses, but in a few places it is quarried for surfacing roads."

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