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San Luis Obispo County – List of Stone Quarries, Etc.*

(* Please note this list does not include sand or gravel quarries.)

  • Alcalde (west of), San Luis Obispo County, California - Freestone Deposit (circa 1890) - Excerpt from the Tenth Annual Report of The State Mineralogist For The Year Ending December 1, 1890, California State Mining Bureau, Sacramento: State Printing Office, 1890, pp. 187.

    San Luis Obispo County, by Myron Angel, Assistant in the Field.

    Freestone.

    “About two miles west of the town of Alcalde, the terminus of the Huron Branch Railroad, the county road runs through a ledge of dark, slate-colored freestone. The ledge courses north 40 degrees west, and dips to the east at an angle of 45 degrees. It is of variable thickness, in places reaching sixty feet. No quarrying or work of any kind has been done. Large pieces, weighing from five hundred pounds to several tons, have fallen from the ledge to the road, and none of the pieces show signs of injurious weathering.

    • “In Sec. 26, T. 21 S., R. 13 E., there is a ledge of freestone of good quality....”

  • Arroyo Grande (south of), San Luis Obispo County, California – the Caen Quarry (AKA Houghton Quarry) (Tuff) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    “Caen Quarry, in Sec. 36, T. 32 S., R. 13 E., M. D. M., and Sec. 26, T. 12 N., R. 35 W., S. B. M.; Los Berros Stone Company, Los Angeles, owner. It is also known as the Houghton quarry, and is about 3 miles south of Arroyo Grande. The tuff is uneven in character, containing in places considerable iron. It has generally a high yellow color, but with white patches and seams containing some lime.”

    Ill. No. 75. Volcanic Tuff Quarry, Los Berros, San Luis Obispo County. Volcanic Tuff Quarry, Los Berros
    • Arroyo Grande (south of), San Luis Obispo County, California – Caen Quarry (Tuff) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist’s Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

      "Caen Quarry, formerly operated in two places, in Sec. 36 T. 32 S., R. 13 E., M. D. M. and in Sect. 26, T. 12 N., R. 35 W., S. B. M., has been idle for years. The material here is a yellow, calcareous cemented, volcanic tuff, which posses considerable strength and is easily cut to shape for building stone. It was quarried in large blocks which were sawed up into desired sizes and hauled to the railroad two miles away. The quarry was last operated about ten years ago and the tuff was used a little for buildings in Arroyo Grande, San Luis Obispo, and Los Angeles. The greatest faults of the tuff are its porosity and the ease with which it stains. The photograph (below) shows this material in the arches and windows of the public library.

      "Bibl.: Bull. 3, p. 159; U. S. G. S. Folio 101."

    Free Public Library, San Luis Obispo. Local building materials were used in its construction. Free Public Library, San Luis Obispo
  • Arroyo Grande (18 miles from), San Luis Obispo, California – Limestone Deposit (Limestone) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "In Lopez Cañon, in the northern part of T. 31 S., R 14 E., M. D. M., about 18 miles from Arroyo Grande, are extensive limestone deposits. The rock is coarsely crystalline, white colored, containing in places some clay and inclusions of shale."

  • Arroyo Grande (east of), San Luis Obispo County, California – Dawson Lowe – Limestone Deposit (Limestone) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "Dawson Lowe, San Luis Obispo. In the northwestern part of T. 32 S., R. 16 E., and eastern part of T. 32 S., R. 15 E., M. D. M., 15 to 18 miles east of Arroyo Grande, in the Huasna country. An extensive deposit of buff-colored limestone."

    Two entries a bit further on the page which refer to the Dawson Lowe entry above:

    "Mrs. R. Porter, Santa Barbara. In the Huasna country. (See D. Lowe, above.)"

    "In the Huasna Country, on Government land, the same limestone is found. (See D. Lowe, above.)

    • Arroyo Grande (east of), San Luis Obispo County, California – Porter Lowe, et al., (Limestone) (Excerpt from "Limestone in California," by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

      "Lowe, Porter, et al. formerly had deposits in the northwest part of T. 32 S., R. 16 E., and eastern part of T. 32 S., R. 15 E., M.D., 15 to 18 miles east of Arroyo Grande. It is an extensive deposit of buff-colored limestone."

    • Arroyo Grande (east of), San Luis Obispo County, California – Miss Julia Newsom - Limestone Outcrop

      Miss Julia Newsom - See: Newsom Springs (near), San Luis Obispo County, California – Newsom Marl Deposit (Marl) below.

  • Cerro Omauldo (north foot of), San Luis Obispo County, California – the Lee Quarry (Porphyritic Rock) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "Lee Quarry, in Sec. 17, T. 30 S., R. 12 E., M. D. M.; Elena Hansan, San Luis Obispo, owner. At the north foot of the Cerro Omaldo, near Chorro Creek; elevation, 625 feet. The rock is of a character similar to that in the Bishop's Peak quarry, only the groundmass has a much lighter and duller gray color. The quarry is in the solid rock, in beds from 1 ½ to 3 feet thick, dipping easterly 45 degrees, which have very smooth planes, in places showing slickensides. The rock was used in the construction of the Southern Pacific railroad, near San Luis Obispo. Has been idle since 1891. (See also XIIIth Report, California State Mining Bureau, p. 623.)

    • Cerro Romualda (sic) (north foot of), San Luis Obispo County, California – Lee Quarry (Porphyritic Rock) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

      "Lee Quarry, in Sec. 17, T. 30 S., R. 12 E., on the north side of Cerro Romaulda (sic), furnished a large tonnage or rock similar to the material from Bishop's Peak, but has been idle for 25 years..

      "Bibl.: Bull. 38, p. 160; R. XIII, p. 623; U. S. G. S. Folio 101."

  • Loma Pelon (near), San Luis Obispo County, California – J. D. Morgan – Limestone Outcropping and Kiln (Limestone & Kiln) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "J. D. Morgan, Arroyo Grande. In Sec. 36, T. 32 S., R. 14 E., M. D. M., near the Loma Pelon, is a limestone cropping from 30 to 40 feet wide, which can be traced for a considerable distance in isolated patches along the highest points of the ridges. The rock is of a dark gray color. Several years ago some lime was burned in a kiln on Section 35 of same township. (See also VIIIth Report, California State Mining Bureau, p. 522.)"

    • Berros (9 miles from), San Luis Obispo County, California – Morgan Limestone Deposit (Limestone) (Excerpt from "Limestone in California," by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

      "Morgan deposit is in sec. 36, T. 32 S., R. 14 E., M.D. Dark-gray outcrops 30 to 40 feet wide are reported at intervals in isolated patches for some distance along the tops of ridges. Some of this material was burned 50 years ago in a kiln on section 35 adjoining. It is about 9 miles by unimproved road from Berros on the railroad

  • Los Berros Creek (south side of), San Luis Obispo County, California – the Moore Quarry (Tuff) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "Moore Quarry, in Sec. 31, T. 12 N., R. 35 W., S. B. M.; P. Moore, Arroyo Grande, owner; leased to the Los Berros Stone Company, Los Angeles. It is on the south side of Los Berros Creek. In the quarry two distinct flows of tuff are readily distinguished. The upper flow, from 10 to 12 feet thick, thins out toward the west. It lies without any parting on the smooth surface of an older flow, dipping slightly eastward. The upper tuff is of more regular character and harder than that at the Caen quarry. It breaks in large but irregular blocks. The lower tuff is much harder than the upper, has a metallic ring, and breaks in small blocks with curved faces like glass. In Los Berros Creek a small gang-saw has been erected. The tuff is sawed here and used for building purposes in Arroyo Grande and San Luis Obispo, and some carloads have been shipped via Port Harford to Los Angeles."

    • Los Berros (near), San Luis Obispo County, California – Moore Quarry (Tuff) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

      "Moore Quarry, in Sec. 31, T. 12 N., R. 35 W., S. B. M., owned by P. Moore of Arroyo Grande was worked by the same company which operated the Caen Quarry, and furnished the same kind of material though perhaps of better quality. The property has been idle for years and the equipment has been removed. The deposit is not far from Los Berros, on the Pacific Coast Railway.

      "Bibl.: Bull. 38, p. 160; U. S. G. S. Folio 101."

  • Los Cerritos, San Luis Obispo County, California - Porphyritic Trachyte Quarries (Porphyritic Trachyte) - Excerpt from the Tenth Annual Report of The State Mineralogist For The Year Ending December 1, 1890, California State Mining Bureau, Sacramento: State Printing Office, 1890, pp. 570.

    San Luis Obispo County, by Myron Angel, Assistant in the Field.

    Los Cerritos.

    “Running midway between the Santa Lucia and the coast hills is a unique line of peaks denominated ‘Los Cerritos’ by the Spanish. These are more or less isolated, separated streams or low passes crossing their course, and standing as a succession of buttes, rising from the southeast of the city of San Luis Obispo and trending northwest, terminating in Morrow Rock, a gigantic cone of trachyte in the ocean off Morro Bay, or the ‘Estero,’ as formerly called. The largest of these peaks is called ‘San Luis,’ one thousand five hundred feet in height, on the northwestern border of the city; ‘Bishop Peak,’ one thousand eight hundred feet high, and the highest of the range, ‘Romualdo,’ ‘Cerrito,’ and San Carlos.

    • “These are chiefly porphyritic trachyte, but bear serpentine about their bases, the smaller hills being almost exclusively of this formation. The trachyte constitutes an available building stone, although very hard chiseling, and can be quarried in as large dimensions as can be handled. The steps of the Court House of San Luis Obispo are made of this rock, and after fifteen years’ use the chisel marks of the stonecutter are not worn away. ‘Morro Rock’ being composed of this and standing in the sea, giving easy and generally safe access to vessels, is deemed exceedingly favorable for furnishing materials for the breakwater in course of construction by the National Government in the bay of San Luis Obispo (circa 1890.)”

  • Morro Bay State Park, San Luis Obispo County, California - Morro Rock Quarry & Quarry at Bautista Ranch (Rock)  (The original version of this web site mentioned these two quarries. In the new version, neither quarry is mentioned.)
    • The Morro Rock Quarry (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

      "Morro Rock Quarry, in Sec. 26, T. 29 W., R. 10 E., M. D. M.; Morrow Bay, United States Government Reservation. The most northern of the line of buttes....Used by A. A. Polhemus for the breakwater at Port Harford. (See also XIIIth Report, California State Mining Bureau, p. 623.)"

    • Morrow Rock, San Luis Obispo County, California – Morrow Rock (Granophyre) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

      "Morro Rock, which is an island at the entrance of Morro Bay and is the farthest northwest of the buttes which form a line from below San Luis Obispo to the ocean, is composed of a granophyre which has been used a good deal at Port Harford for breakwater construction. The quarry is on a government reservation and is now idle. (circa 1915-1916)"Bibl.: Bull. 38, p. 161; U.S.G.S. Folio 101."

      Morrow Rock, San Luis Obispo County, California - Also see: San Luis Obispo County, California – Bishop's Peak (Cerro Obispo) Quarry (Porphyritic Rock) below.

  • Newsom Springs (near), San Luis Obispo County, California – Miss Julia Newsom (Limestone Outcrop) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "Miss Julia Newsom, Newsom Springs, Rancho Santa Manuela, 2 ½ miles east of Arroyo Grande. The limestone crops out along the hillside, from 35 to 50 feet above the cañon, in a flat bed 5 to 6 feet wide. It is light colored, and mixed with clay. Some lime was burned here several years ago."

    • Newsom Springs (near), San Luis Obispo County, California – Newsom Marl Deposit (Marl) (Excerpt from "Limestone in California," by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

      "Newsom marl deposit is near Newsom Springs and 2 ½ miles east of Arroyo Grande. A bed of soft limestone 6 feet thick outcrops on a hillside. Some lime was burned 50 years ago or more."

  • Morro (7 miles from), San Luis Obispo County, California – Dan Tomasini Ranch (Rhyolitic Rock Deposit) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

    "On the ranch of Dan Tomasini, 7 miles from Morrow, there is an extensive deposit of a rhyolitic rock of light brown color, which shows to advantage when rough dressed. M. P. Rolita is using a little of it for monumental work, but it is too remote from transportation for active exploitation."

  • Morro (8 miles from) San Luis Obispo County, California – the Walter Ranch (Granitic Rock Deposit) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

    "Walter Ranch, Chas. Walter, owner, 8 miles from Morro. A deposit of a fine-grained, light-colored rock occurs which contains a little hornblende and biotite and approaches a granite in appearance and composition. It takes a fair polish and would be valuable if better situated. M. P. Rolita is using some of this stone experimentally in his monument work."

  • Musick (north of), San Luis Obispo County, California – the Kesseler Onyx Deposit (Onyx) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "Kesseler Onyx Deposit, in Secs. 9 and 16, T. 31 S., R. 15 E., M. D. M.; F. A. Kesseler, administrator, 325 Fair Oaks street, San Francisco; 5 miles north of Musick P. O., and 17 miles northeast of Arroyo Grande, the nearest railway station. A deposit of beautiful onyx marble, discovered more than twenty years ago. About 1890, Mr. Kesseler built a wagon road at considerable expense from Musick, and during the 90's it is said that more than 1000 tons were shipped from this quarry. None has been shipped during the past five years, as the estate has been in the probate court.

    "Onyx marble has been quarried at two different points. The main opening lies on the east side of the hill near the head of a small cañon, about one mile east of the county road. The opening is about 50 feet long and 20 feet high, and the total thickness exposed is about 15 feet.

    "The onyx marble occurs in somewhat irregular layers, from 1 inch to 8 or 10 inches, and in one place 30 inches in thickness. In places it is banded or variegated, and in some layers it is a white, massive, compact stone. It is true aragonite, and hence has a higher specific gravity than ordinary limestone. The stone is translucent and takes a brilliant polish. On the outcrop it has a yellowish-brown surface stain. In a few places the seams are filled with red hematite, which occasionally impregnates the stone, making bright red blotches or bands. Portions of the stone are banded with a dark green color. In parts of the deposit the stone contains small cavities up to an inch in diameter, which disfigure the marble, but most of it is solid between the seams. It has been broken out in blocks from 3 to 6 feet square, but blocks with a much larger surface could be obtained by careful quarrying.

    "There are a great many tons of good, sound onyx marble exposed at this point, and the supply beneath the surface is probably considerable, but there is nothing to indicate the depth to which these layers extend.

    "There is a smaller opening on the west side of the hill, about half a mile west of the main opening. At this point the stone is white, with a very faint banding, and occurs in two layers varying from 1 to 6 inches thick, averaging about 3 inches.

    "Onyx marble in irregular masses is also exposed at the mineral spring on the hill between two quarry openings. In several places aragonite is in process of formation in cavities in the shales and sandstones through which the mineral water trickles. In several places in the shales there are the incrustations of flos ferri, a delicate, coral-like form of aragonite.

    "The onyx marble in this locality has been formed by the mineralized water that seeps out near the top of the hill and trickles down over the shales and sandstones. The water is now highly charged with sodium chloride and other salts, and during the dry season forms an extensive deposit along the several watercourses that radiate from the high land on which the springs are located. There are several small springs or seeps in this area, from all of which comes a mineral water strong with different salts in solution. The water has been shipped in barrels to some of the hospitals in the State, because of its great curative properties.

    "Many polished specimens of the Kesseler onyx marble are on exhibition in the museum of the California State Mineral Bureau and in the Golden gate Park museum. A chemical analysis of the stone shows it to be fairly pure carbonate of lime."

    Chemical Analysis of San Luis Obispo County Onyx Marble
    Ill. No. 46. Aragonite Quarry (Kesseler's Onyx Marble), San Luis Obispo Co. Aragonite Quarry (Kesseler's Onyx Marble)
    Ill. No. 47. Aragonite Quarry (Kesseler's Onyx Marble), San Luis Obispo Co. Aragonite Quarry (Kesseler's Onyx Marble)
  • Nipomo Creek, San Luis Obispo County, California – Santa Maria Rock Company (Crushing Plant) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

    "Santa Maria Rock Company, now defunct (circa 1915-1916), operated a small rock crushing plant on Nipomo Creek, which supplied a few thousand tons of material for highway construction early in 1915."

  • Oak Flat, San Luis Obispo County, California - Limestone Quarry (Limestone) - Excerpt from the Tenth Annual Report of The State Mineralogist For The Year Ending December 1, 1890, California State Mining Bureau, Sacramento: State Printing Office, 1890, pp. 584.

    San Luis Obispo County, by Myron Angel, Assistant in the Field.

    Lime.

    • “Limestone in various parts of the county, and to ledges of limestone may be added, for the purpose of lime, the vast beds of fossil oyster shells that are found in many localities, as near the Oceanic Quicksilver Mine, on the Santa Margarita Ranch, about the headwaters of the Arroyo Grande, and many others. These beds have furnished convenient sources for lime, although not making a first class article for masonry work. At Oak Flat, near Paso Robles, is a large bed of limestone, which is burned for lime quite extensively, producing an excellent article.”

  • Paso Robles (19 ½ miles from), San Luis Obispo County, California – Dubost Limestone Deposit (Limestone) (Excerpt from "Limestone in California," by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

    "Dubost limestone deposit is on the Dubost Ranch in the NW ¼ sec. 30, T. 26 S., R. 10 E. and NE ¼ sec. 25,T. 26 S., R. 9 E., M.D. The property was assessed to Frank K. and Mary Dubost in 1946 and was being prospected by H. W. Gould & Company with a light diamond-drill outfit. It is about 19 ½ miles by road from Paso Robles.

    "The deposit extends for 3600 feet about N. 75 W. on this property, and for probably a quarter of a mile farther on adjacent land which slopes steeply toward Franklin Creek. From north to south it covers from 1200 to 1500 feet. The vertical range is 400 feet as measured by aneroid, the high ridge to the south rising 400 feet above the site of an old lime kiln where stone was quarried and burned on a small scale over 50 years ago. On the topographic map of the U. S. Geological Survey the summit of the ridge is shown to have an elevation of 1950 feet. The deposit is broken into terraces, dropping to the north, and indicating step faulting associated with two faults, one of which bounds the high ridge on the south and separates the Miocene limestone from the Jurassic rocks. The summit ridge, forming the highest terrace, shows the most extensive limestone outcrops. They are dust colored to white, somewhat siliceous, dense, hard, and of medium-crystalline texture. While it is undoubtedly of the same age as the Lime Mountain deposit, it shows much less fossil evidence and somewhat greater metamorphism, probably due to proximity to the faults. The second bench is 180 feet (aneroid) below the summit ridge, and is separated from it by a nearly vertical face, probably representing subsidence of this amount on the north side. The third or lowest bench, on which diamond drilling was going on at time of visit, is 100 feet vertically below the second. From there to the road level near the old kiln there is a gentler slope with an additional drop of 120 feet.

    "H. W. Gould & Company report that a total of 1742 feet of diamond drilling was done in 14 holes drilled in the lowest bench in 1946. They computed the average CaCO3 content as 91.32 percent and the average SiO2 content as 5.17 percent, including siliceous material deposited in the leached surface layer. They think a product carrying over 95 percent CaCo3 and a minimum of 2 ½ percent silica could be attained by proper screening. Only a few samples were analyzed for MgO, and these showed less than 0.25 percent. They estimate from preliminary examination that the deposit contains over 50,000,000 tons, of which only 1,000,000 to 2,000,000 tons has been tested by drilling and analysis.

    "The writer took a surface sample across a width of about half a mile along the summit of the ridge from east to west. This gave the following analyses as reported by Abbot A. Hanks, Inc.

    Insoluble, 5.59 percent
    Fe & Al oxides, 0.60 percent
    CaCO3, 92.8 percent
    MgCO3, 0.81 percent

    "The deposit is favorably located for operation, with a good site for a plant. Water is reported to be available and late in 1946 electric power was only 1 ½ miles distant."

  • Paso Robles (west of), San Luis Obispo County, California – Limestone Exposure (Limestone) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "Near Oak Flat, west of Paso Robles, an exposure of limestone is reported. (See Xth Report, California State Mining Bureau, p. 584.)"

  • San Luis Obispo (east of), San Luis Obispo County, California – Lopez Canyon Limestone Group (Limestone) (Excerpt from "Limestone in California," by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

    "Lopez Canyon group of three claims was located in 1924 close to the southeastern corner of sec. 36, T. 30 S., R. 13 E., M.D., where Fern Canyon enters Lopez Canyon from the west, about 7 miles due east of San Luis Obispo. The bottom of Lopez Canyan (sic) has an elevation of 1200 feet there, while the ridge on the west rises to elevations of 2300 to 2800 feet with no road within 4 miles in that direction. A road runs 15 miles from Arroyo Grande (on the railroad) to the claims.

    "The Monterey beds, of which the limestone here forms a part, lie in a deep syncline in this region according to H. W. Fairbanks (04),* and the determination of actual thickness is also rendered difficult by brush. An apparent thickness of 100 feet or more is reported at the mouth of Fern Canyon, with dip of 45 SW.

    (* Harold Wellman Fairbanks, "Description of the San Luis quadrangle, Cal." U. S. Geol. Survey, Geol. Atlas, San Luis folio (no. 101), 14 pp. maps, 1904)

    "No analysis of the limestone is available. A little of it was burned experimentally by the owners in a small kiln. So far as known there has been no recent activity."

  • San Luis Obispo, San Luis Obispo County, California - Los Berros Yellow Sandstone Quarry & Bishop's Peak Granite (Sandstone & Granite) (photograph and history of the Library/Museum).

    The building, which is today the San Luis Obispo County Historical Museum, was originally the San Luis Obispo Carnegie Library. Part of the construction materials for the building were Los Berros Yellow Sandstone for the arch and window detailing and Bishop's Peak Granite was used for the foundation.

  • San Luis Obispo, San Luis Obispo County, California - Sunset Monument and Building Works (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

    "Sunset Monument and Building Works, M. P. Rolita, proprietor, San Luis Obispo. The owner and occasionally an extra man are employed in making monuments, curbing, coping, and house foundations. The rock from Bishop's Peak is used for all unpolished require polishing (sic), the uses the andesite granophyre from Bishop's work is rather well liked for curbing, especially on account of the way it fractures. Hand tools are used. The rock is of two shades and degrees of hardness, because of the difference in weathering."

  • San Luis Obispo (northeast of), San Luis Obispo County, California – the Frank Tate Ranch (Rock Crusher) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

    "On the Frank Tate Ranch, 2 miles northeast of San Luis Obispo, a small rock crushing plant, equipped with a gyratory crusher, was put up early in 1915. The rock was an extremely hard and tough basic intrusive which fractured in long splintery pieces. The man who was operating the plant found it so costly to reduce the material that he was forced to abandon work after selling a few thousand tons, although the Highway Commission was paying $1.00 per ton and he was getting the material on a very low royalty basis."

  • San Luis Obispo County, California – Alberti Ranch Red Rock Quarry (Stone) (active ca 1996) (From Mines and Mineral Producers Active in California (1994-1995), Special Publication 103 (Revised 1996), California Department of Conservation, Division of Mines and Geology, in cooperation with California Department of Conservation, Office of Mine Reclamation. Used with permission, California Department of Conservation, California Geological Survey.)

    Mine name: Alberti Ranch Red Rock Quarry; Operator: Madonna Construction Company; Address & County: P. O. Box 3910, San Luis Obispo, CA 93403 County; Phone: (805) 543-0300; Latitude: 35.30, Longitude: -120.69, and Mine location number: Map No. 666; Mineral commodity: Stone.

  • San Luis Obispo County, California – Bishop's Peak (Cerro Obispo) Quarry (Porphyritic Rock) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "Bishop's Peak (Cerro Obispo) Quarry, in Sec. 21, T. 30 S., R. 12 E., M. D. M.; Dr. G. B. Nichols, San Luis Obispo, owner; J. W. Wyley, superintendent. There are two quarries on this property. From the old quarry at the southwest corner of the butte large blocks were taken by A. A. Polhemus and the City Improvement Company of San Francisco for the Government breakwater at Port Harford, but lately this quarry has not been used. The present quarry is in the southeast corner of the butte, elevation 1000 feet. As yet only boulders have been quarried, the face having just reached the solid rock, which has a porphyritic character, and breaks easily, requiring very little powder. The rift is not appreciable, the fracture occurring generally on a curved plane, which, however, is very smooth. The rock can be easily dressed and takes a good polish. It is used for rubble masonry, coping stone, curb stone, etc. It was used in the Presbyterian Church, and the basement of the Free Library, San Luis Obispo.

    "In 1896 Mr. William Irelan made an analysis of the rock from the old quarry, giving it silica, 64.15 per cent, and a specific gravity of 2.58, equal to 161 pounds per cubic foot."

    • San Luis Obispo County, California – Bishop's Peak Quarry (Andesite Granophyre) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

      "Bishop's Peak Quarry, owned by L. H. Nichols, 1015 Monadnock Building, San Francisco, was formerly operated at two openings on the side of Cerro Obispo, which lies just outside of San Luis Obispo, and was served by a spur track from the narrowgauge railway. No work has been done here for years. The rock, an andesite granophyre of dark gray color and subconchoidal fracture, has been used extensively for foundations and curbings, and a few buildings in San Luis Obispo, including one of the schools are built entirely of it.

      Bibl.: Bull. 38, p. 153; U.S.G.S. Folio 101."

  • San Luis Obispo County, California – Cerro Obispo Quarry

    (Cerro Obispo Quarry - See: San Luis Obispo County, California – Bishop's Peak (Cerro Obispo) Quarry above.)

  • San Luis Obispo, San Luis Obispo County, California – the City of San Luis Obispo's Plant (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "City of San Luis Obispo's Plant, on Higuero street, crushing chert rock."

  • San Luis Obispo County, California – Cambria Pit (Stone) (active ca 1996) (From Mines and Mineral Producers Active in California (1994-1995), Special Publication 103 (Revised 1996), California Department of Conservation, Division of Mines and Geology, in cooperation with California Department of Conservation, Office of Mine Reclamation. Used with permission, California Department of Conservation, California Geological Survey.)

    Mine name: Cambria Pit; Operator: Negranti Construction; Address & County: P. O. Box 198, Cayucos, CA 93430, San Luis Obispo County; Phone: (805) 995-3357; Latitude: 35.54, Longitude: -121.05, and Mine location number: Map No. 672; Mineral commodity: Stone.

  • San Luis Obispo (south of), San Luis Obispo County, California – Dougherty Quarry (Crushed Rock/Sandstone) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

    "Dougherty Quarry is owned by A. A. Dougherty of San Luis Obispo and is 3 miles south of that city, in Sec. 9, T. 31 S., R. 12 E. Development was initiated in September, 1914, by Otto Wannack. The holdings comprise 15 acres. The rock is chiefly Franciscan sandstone, which crops in a steep wall, permitting easy quarrying. Holes 15' to 22' deep are put down by hand and the face blasted off by dynamite. The big blocks are broken to one-man size. Before tramming to the crusher the material is sorted into two grades: the blue, well-cemented sandstone and a softer, brownish rock, which comes from the top and is not as clean as the blue.

    "The stone is reduced to about 3" size and is stored partly in a 500-ton bin and partly over trestles in big piles in the open. Power is furnished by gasoline engines at a cost of 2¢ per h.p.-hour. There are 7 engines, including one of 80 h.p. and one of 50 h.p. Other equipment includes one 7 ½" and 3" gyratory crusher, 24 cars, 500-ton bin, and buildings for office, boarding-house, and sleeping quarters. A spur track from the Pacific Coast Narrow Gauge Railroad furnishes transportation. The capacity of the plant is 300 tons per day. Past production has been at the rate of about 50,000 tons per annum. A crew of 75 men are employed at wages ranging from 25¢ per hour up. There is little overburden and, considering the small investment in plant, the cost of production per ton is not extremely high.

    "The bulk of rock sold has been for use on the state highway system. The hard, blue material is excellent for concrete and is used for the central railroad; the brown sandstone is used for shoulder-work and for macadam, where the duty is not so heavy."

  • San Luis Obispo County, California – Adelaide Dubost (Limestone Quarry) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)

    "Dubost, Adelaide. In Secs. 18 and 19, T. 26 S., R. 10 E. M. D. M., on the old Tartalja place, is a large exposure of limestone. Formerly A. Gould burned lime here. Idle for the last few years."

  • San Luis Obispo County, California – Froom Ranch Pit (Stone) (active ca 1996) (From Mines and Mineral Producers Active in California (1994-1995), Special Publication 103 (Revised 1996), California Department of Conservation, Division of Mines and Geology, in cooperation with California Department of Conservation, Office of Mine Reclamation. Used with permission, California Department of Conservation, California Geological Survey.)

    Mine name: Froom Ranch Pit; Operator: Madonna Construction Company; Address & County: P. O. Box 3910, San Luis Obispo, CA 93403, San Luis Obispo County; Phone: (805) 543-0300; Latitude: 35.25, Longitude: -120.69, and Mine location number: Map No. 673; Mineral commodity: Stone.

  • San Luis Obispo County, California – Grieb Ranch Quarry (Stone) (active ca 1996) (From Mines and Mineral Producers Active in California (1994-1995), Special Publication 103 (Revised 1996), California Department of Conservation, Division of Mines and Geology, in cooperation with California Department of Conservation, Office of Mine Reclamation. Used with permission, California Department of Conservation, California Geological Survey.)

    Mine name: Grieb Ranch Quarry; Operator: Harley Green Stone Co.; Address & County: P. O. Box 803272, Santa Clara, CA 91380, San Luis Obispo County; Phone: (805) 253-1067; Latitude: 35.21, Longitude: -120.52, and Mine location number: Map No. 674; Mineral commodity: Stone.

  • San Luis Obispo, San Luis Obispo County, California – H. J. Griffith (Monument Business) (Excerpt from Report XV of the State Mineralogist, Mines and Mineral Resources of Portions of California, Chapters of State Mineralogist's Report Biennial Period 1915-1916, Part V. Monterey, San Benito, San Luis Obispo, Santa Barbara, Ventura counties, California State Mining Bureau, 1919, pp. 595-769.)

    "H. J. Griffith does a small business cutting stone at San Luis Obispo. For the bases of all of his monuments, where the stone does not require polishing, he uses the andesite granophyre from Bishop's Peak. His equipment includes a gasoline engine and air hammer drill."

  • San Luis Obispo County, California – Homeplace Pit (Stone) (active ca 1996) (From Mines and Mineral Producers Active in California (1994-1995), Special Publication 103 (Revised 1996), California Department of Conservation, Division of Mines and Geology, in cooperation with California Department of Conservation, Office of Mine Reclamation. Used with permission, California Department of Conservation, California Geological Survey.)

    Mine name: Homeplace Pit; Operator: "Private"; Address & County: 1228 Drake Circle, San Luis Obispo, CA 93405, San Luis Obispo County; Phone: (805) 541-1094; Latitude: 35.31, Longitude: -120.71, and Mine location number: Map No. 678; Mineral commodity: Stone.

  • San Luis Obispo County, California – Rancho San Simeon (Rock) (active ca 1996) (From Mines and Mineral Producers Active in California (1994-1995), Special Publication 103 (Revised 1996), California Department of Conservation, Division of Mines and Geology, in cooperation with California Department of Conservation, Office of Mine Reclamation. Used with permission, California Department of Conservation, California Geological Survey.)

    Mine name: Rancho San Simeon; Operator: Rancho San Simeon; Address & County: P. O. Box 455, Cambria, CA 93428, San Luis Obispo County; Phone: (805) 927-3588; Latitude: 35.60, Longitude: -121.12, and Mine location number: Map No. 692; Mineral commodity: Rock.

  • San Luis Obispo (north of), San Luis Obispo County, California – Santa Margarita Limestone Deposit (Limestone) (Excerpt from "Limestone in California," by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

    "Santa Margarita deposit 2 to 3 miles north of San Luis Obispo, is reported to show a width of 20 feet of brown crystalline limestone over a length of a mile."

  • San Luis Obispo County, California – Shell Deposits (Limestone) (Excerpt from "Limestone in California," by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

    "Shell deposits of good size occur near the Oceanic mine and on San Simeon Creek 4 or 5 miles inland."

  • San Luis Obispo County, California – Whylie's Rhyolite Quarry (Rhyolite) (From The Structural and Industrial Materials of California, Bulletin No. 38, California, State Mining Bureau, San Francisco, California, 1906.)
    Ill. No. 74. Whylie's Rhyolite Quarry, San Luis Obispo County. Whylie's Rhyolite Quarry
  • San Miguel (26 miles from), San Luis Obispo County, California – Lime Mountain Limestone Deposit – San Miguel Lime & Development Company (Limestone) (Excerpt from "Limestone in California," by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

    "Lime Mountain Deposit (San Miguel Lime & Development Company). A total of 600 acres, comprising parts of secs. 9, 10, and 15, T. 26 S., R. 9 E., M.D., is assessed to Ed. W. Bolt. The limestone deposit forms the flattish top and upper slopes of Lime Mountain, elevation 2271 feet, in the west half of section 15. The limestone-covered area at the 200-foot contour is about 90 acres. San Miguel, the rail shipping point, is 265 miles to the northeast. Of this, all but 2 miles is dirt road but the steeper parts favoring loaded trucks.

    "Charles Taylor began development of the deposit about 1932 and the first reported sale of limestone was in 1933. From 1933-43 the property has been the sole limestone producer in the county. The stone has been found satisfactory for making lime in vertical kilns for use in refining beet sugar, and substantial sales have been made for that use, particularly at Salinas. Taylor transferred his interests about 1943 to the present holder, who made large shipments in 1945. Plans and surveys have been made for road changes and improvements, as well as for the possible building of a railroad spur to the deposit, and shipments were temporarily suspended in 1946, to await realization of some of these plans. Production was resumed in 1947. Drilling and examinations are reported to indicate 75,000,000 tons or more, but details were not available at the time of the author's visit in May 1946, when no one was on the property.

    "Several small quarries have been opened near the top of the mountain. The three smallest, which gave only limited backs, appear to have been idle recently. The later work was done from the south slope with the floor at 2130 foot elevation (aneroid). This had been opened for a distance of 325 feet east to west and for a maximum advance south to north, of 150 feet. The highest part of the face was 100 feet above the floor in May 1946, and the quarry floor was triangular in plan. In the total distance of 325 feet, there was a core of solid stone 175 feet thick, surrounded by broken and blocky rock which made considerable waste. The old northwest pit is about 165 by 225 feet with a maximum depth of 40 feet below the tip of the mountain. There is another old quarry at 1975 feet elevation (aneroid) just southwest of the main quarry. Much of the face of this old quarry is in loose slide rock.

    "The limestone is light buff to off white in color. On the surface near the summit, shells are common, including a large mussel classified as Mytilus coalingensis by G. Dallas Hanna of the California Academy of Sciences. This indicates the Santa Margarita formation of upper Miocene age. The surface layer carrying loose shells is underlain by a feet few of distinctly fossiliferous limestone showing such shells, passing in depth to a tough and compact stone in which the crystals are of medium size, showing few broken shell remains, but giving the fetid ordor (sic) of stinkstein when hammered.

    "The following analyses of two samples were made by Abbot A. Hanks, Inc., June 1946. No. 1 was taken across 175 feet in the new quarry at a depth of 100 feet. No. 2 was from the old northwest quarry.

    Analyses of limestone, Lime Mountain, San Luis Obispo County

    No. 1 (insoluble percent) 3.19 percent; (Fe & Al oxides) 0.50 percent; (CaCO3) 95.15 percent; (MgCO3) 1.06 percent.

    No. 2 (insoluble percent) 3.80 percent; (Fe & Al oxides) 0.39 percent; (CaCO3) 94.61 percent; (MgCO3) 1.10 percent.

    "Although no one was available at the property to show property lines or advise depth to which limestone has been proved by drilling, the area of the outcrop, and the work already done in the quarries are sufficient to indicate a large deposit. The limestone outcrop is continuous for 2500 feet from east to west across the summit of the mountain, and about 1225 feet north to south, as measured by pacing. A deposit of these dimensions would contain about 25,520,000 tons per 100 feet in depth. The floor of the old quarry on the southwest side of the mountain is at 1975 feet elevation (aneroid) or nearly 300 feet below the summit. On the north side, the slope is covered by soil and brush and no limestone in place and little float was seen below 2050 feet elevation. A little below this, a small open cut is marked 'Test hole No. 2, Elevation 289 feet.' This shows soil underlain by brown sandy shale. No outcrops of any rock except limestone were noted within the limestone-covered area described.

    "In the past, the limestone broken in the open quarries by bank blasting has been loaded on trucks by a Northwest shovel operated by a 4-cylinder gasoline engine and with a 1-cubic-yard bucket. It was hauled a few hundred feet to a rock breaker powered by a 4-cylinder Diesel engine. Crushed stone, 2 to 6 inches, was sent by a short belt conveyor to bins on the east slope for loading on trucks. An Ingersoll-Rand 250 portable compressor furnished air for drills.

    "The road from the new quarry level drops over 1300 feet in less than 5 miles."

    Plate 34-A. New Quarry - Lime Mountain limestone deposit, San Luis Obispo County. Apex is 100 feet above quarry floor. New Quarry - Lime Mountain limestone deposit
    • San Luis Obispo County, California – Lime Mountain Company (Limestone) (active ca 1996) (From Mines and Mineral Producers Active in California (1994-1995), Special Publication 103 (Revised 1996), California Department of Conservation, Division of Mines and Geology, in cooperation with California Department of Conservation, Office of Mine Reclamation. Used with permission, California Department of Conservation, California Geological Survey.)

      Mine name: Lime Mountain Company; Operator: Lime Mountain Company; Address & County: P. O. Box 1797, Paso Robles, CA 93447, San Luis Obispo County; Phone: (805) 238-4984; Latitude: 35.67, Longitude: -120.99, and Mine location number: Map No. 680; Mineral commodity: Limestone.

  • Santa Lucia Mountains, San Luis Obispo County, California - “California Onyx” (Aragonite) Quarries (“California Onyx” - Aragonite) - Excerpt from the Tenth Annual Report of The State Mineralogist For The Year Ending December 1, 1890, California State Mining Bureau, Sacramento: State Printing Office, 1890, pp. 584.

    San Luis Obispo County, by Myron Angel, Assistant in the Field.

    “California Onyx” (Aragonite).

    “This property is situated in the heart of the Santa Lucia Mountains, a region of precipitous hills and cañons. The ledge or ledges, there being two openings half a mile a part, are on Secs. 9 and 16, T. 31 S., R. 15 E., M.D.M., at an elevation of one thousand eight hundred feet above the level of the sea.

    “The locality appeared so difficult to access, the croppings looking rough and uninviting, and no one knowing the value of the material, or having enterprise to ascertain its worth, the property was easily purchased by Kessler Bros., of San Francisco and New York, who then obtained patents for two claims of one thousand five hundred feet in length each, by six hundred feet in width, under the United States mining laws.

    “A little prospecting was done and croppings found in two places about half a mile apart, the one on the northern slope of the ridge and the other on the southern, the hill rising about eighty feet between them. Whether these are one vein or not is unknown. The strike of the northern croppings is directly towards the southern. The strike of the southern croppings is diagonal to the course of the other. The rock of the northern is milky white, and that of the southern of variegated colors. From these croppings a few tons of rock have been taken to San Francisco , and there sawed and polished into various articles of ornament.

    “In May of the present year (1890) a wagon road was constructed from Musick to the mines, a distance of five miles. Mr. Kessler informed the writer that the rock in its rough state was worth $100 a ton in San Francisco. The cost of transportation from the mine to San Francisco is about $14 per ton. A hundred or more tons of the rock stand above the ground in croppings which can be taken in pieces as large as ten feet square, apparently without a flaw. A loose block was shown, said to weigh three tons, out of which thirty slabs would be sawed of ten or twelve square feet each, and which would be worth when polished, at least $10 per square foot. When polished the colors are a yellow, green, pink, blue, golden, red, and white, in lines and curved beautifully blending.

    “This valuable product of the county, for which there appears a vast quantity, will be taken chiefly to New York and Europe to be worked into articles of use and ornament.

    “The inclosing rock is sandy slate, the ledges of onyx standing nearly perpendicular, and having a thickness of about sixteen feet. In the middle of the vein, at the present southern opening, is a fissure of about ten inches broad and of unknown depth, as small stones dropped in go rattling for some time, and at last are heard to strike water in the depth of the cavity.

    • “Near the summit of the hill, on the line of the vein, is a spring of medicinal water flowing about half a barrel an hour. The water has a pleasant salty taste, is a strong purgative, and is very effective as a wash in curing cutaneous affections. No analysis of the water has been made.”

  • Santa Lucia Mountains, San Luis Obispo County, California – Tassajara Group of 3 Limestone Claims (Limestone) (Excerpt from "Limestone in California," by Clarence A. Logan, California Journal of Mines and Geology, Vol. 43, No. 3, July 1947, California Division of Mines, San Francisco, California, pp. 175-357. Used with permission, California Department of Conservation, California Geological Survey.)

    "Tassajara group of 3 claims is in secs. 21 and 28, T. 29 S., R. 12 E., M.D., on a deposit of coarse crystalline white limestone on the east slope of the Santa Lucia Mountains near the summit, at the head of Tassajara Creek. It is 3 miles from the highway and railroad.

    "Veins of limestone, the largest 12 to 14 feet wide, have been traced the length of two claims and some prospecting was done in open cuts over 20 years ago (Laizure, C. McK 25, p. 522).* The claims were owned then by S. Aumaier, San Luis Obispo. The limestone occurs in the lower Cretaceous (Toro) shale.

    "The following analysis was by Smith Emery & Company (Laizure, C. McK, p. 522).*

    (* C. McK Laizure, San Francisco Field Division, "San Luis Obispo County," California Mining Bureau Report 21, pp. 499-538, 1925.)

    SiO2, 0.45 percent; Al2O3, 0.19 percent; Fe2O3, 0.85 percent; Mn3O4, 0.80 percent; CaO, 54.24 percent; MgO, 0.42 percent; Loss on ignition, 43.40 percent.

    "The following limestone deposits have been noted in past reports, but no details have been given: Almaden deposit, Porter Lowe, et al, Morgan deposit, Newsom marl deposit, Nipomo Deposit, Santa Margarita deposit, and Shell deposits.*

    (* The deposits listed in the above paragraph are listed above according to location. The entries in the book include a little bit more information on the deposits.)

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