With the field for development along these lines which is open in California, it seems almost certain that some time in the future will see this branch of the mineral industry adding its share to the total of the wealth and productiveness of this state.

Total amount and value of asbestos production in California since 1887, as given in the records of this Bureau, are as follows:

Bibliography: State Mineralogist Report XII. Bulletin 38.

The output of crude barytes during 1915 was 410 tons, valued at $620, from Mariposa and Los Angeles counties, as compared with the 1914 production of 2,000 tons, worth $3,000. This indicates a spot value of only $1.50 per ton, approximately, for the 1915 product. As a matter of fact barytes is ordinarily sorted and ground before being put on the market, and in this prepared condition brings from $10 to $15 per ton. The principal use of this material is in the paint industry. Minor uses are in tanning of leather, manufacture of paper and rope, and sugar refining. A grinding and chemical plant is in operation at Melrose, Alameda County, making a specialty of barium compounds; and another at South San Francisco.

Known occurrences of this mineral in California are located in Butte, Mariposa, San Benito, San Bernardino, Shasta, Calaveras, Inyo and Nevada counties. The deposit at El Portal, in Mariposa County, has given the largest commercial production to date. The tonnage above recorded is in part, witherite (barium carbonate, BaCO,) from El Portal. This is the first commercial production of the carbonate in the United States, of which we are able to find any record (as we pointed out in our Press Bulletin 35, April 28, 1916). The El Portal witherite and barite are both high grade. The current year, 1916, will show a

considerable output from a new deposit being opened up on Fremont's Peak in San Benito County.

The first recorded production of barytes in California, according to the statistical reports of the State Mining Bureau, was in 1910. The annual figures are as follows:

Bibliography: State Mineralogist Reports I, IV, IX, XII. Bulletin 38.

At one time or another in the history of the state, pottery clay has been quarried in thirty-three of its counties. In this report "pottery clay" refers to all clays used in the manufacture of red and brown earthenware, flower pots, ornamental tiling, architectural terra cotta, sewer pipe, etc., and the figures for amount and value are relative to the crude material at the pit, without reference to whether the clay was sold in the crude form, or whether it was immediately used in the manufacture of any of the above finished products by the producer. It does not include clay used in making brick and building blocks.

During 1915 producers in seven counties reported an output of 157,866 tons of clay, having a spot value of $133,141 for the crude material, as compared with the 1914 production of 179,948 tons worth. $167,552.

A tabulation of the direct returns from the producers, by counties, for the year 1915, is shown herewith:

Amount and value of clay-pottery output in California since 1887, are given in the following table:

In the present report, dolomite is for the first time made the subject of a separate classification. Previously it has been included under limestone. Limestones are frequently more or less magnesian-bearing, and a chemical analysis is often necessary to definitely decide as to whether they are calcite or dolomite; the latter standing intermediate between magnesite (MgCO) and calcite (CaCO3). As dolomite, as such, has been found to have certain distinctive applications, we have deemed it worthy of a separate classification.

The major portion of the tonnage shipped in 1915 was utilized as a refractory lining in open-hearth steel furnaces, as a partial substitute for magnesite. A portion was used for its carbonic acid gas (CO2), and part for its magnesia. A greatly increased output is anticipated for the year 1916, as we are informed that one company with quarries in San Benito and Monterey counties has contracted to furnish calcined dolomite to one of the large paper mills. As this dolomite has been found to contain the proper proportions of lime and magnesia, it will replace an artificial mixture of calcined limestone and magnesite in the manufacture of paper from wood pulp.

The production of dolomite for the year 1915 amounted to 4,192 tons, valued at $14,504, and came from a total of five quarries in the following counties: Inyo, San Benito, San Bernardino and Tuolumne.

FELDSPAR.

Bibliography: Bulletin 67.

Feldspar was produced by one operator in Monterey and three in Tulare County during 1915, to the amount of 1,800 tons, valued at $9,000. Feldspar production only dates back to 1910 in this state. The mineral is a constituent of many rocks, but can only be commercially produced from pegmatites where the crystals are large and quite free from impurities. The open cut method of mining this material is commonly used. Manufacturers of enamel wares and pottery buy most of the better grades of feldspar produced. Small quantities are used in the manufacture of glass and scouring soaps, and the more impure material is utilized as "chicken grit," in making various brands of roofing, and in other ways. Various experiments have been made with the potash feldspars in the attempt to prove their value as a fertilizer, with more or less negative results, so far.

Total amount and value of feldspar production in California since the inception of the industry are given in the following table, by years:

Fuller's earth production in California during the year 1915 amounted to 692 tons, valued at $4,002, as compared with 760 tons, valued at $5,928, in 1914.

This material is soft and friable, and, in general, resembles a clay. It has no definite mineralogical composition, and its commercial value is determined by its physical properties, i. e., texture, and filtering and absorbent properties.

In California, fuller's earth is used in clarifying both refined mineral and vegetable oils, although its original use was in fulling wool, as the name indicates. During 1915 the production came from Calaveras, Kern, Kings and Solano counties. A large deposit of high grade fuller's earth is found near Elsinore in Riverside County.

It was first produced commercially in this state in 1899, and the total amount and value of the output since that time are as follows:

Bibliography: Bulletins 37, 64, 67. State Mineralogist Report II. Accounting for the production of gems in California is somewhat unsatisfactory, owing to the widely scattered places at which stones are gathered and marketed in a very small way. The following table shows the production by counties during 1915:

California tourmalines are decidedly distinctive in coloring and "fire" as compared to foreign stones of this classification. The colors range from deep ruby to pink, and various shades of green; also more recently a blue tourmaline has been found.

Two of our California gem stones, kunzite and benitoite, are not found elsewhere in the world; and these, each in but a single locality here: the former in the Pala Chief Mine in San Diego County, and the latter in the Dallas Mine in San Benito County.

Some rhodonite was taken out in Siskiyou County in 1915, and used for decorative purposes, its value being included in the marble figures.