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

Feldspar was produced in Monterey and Tulare counties during 1914, to the total amount of 3,530 tons, valued at $16,565. 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.

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 1914 amounted to 760 tons, valued at $5,928, as compared with 460 tons worth $3,700 in 1913.

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 principally in clarifying refined mineral oils, although its first use was in fulling wool, as the name indicates. During 1914 the production by counties was as follows:

It was first discovered in this State in 1899, and the total amount and value of the production since that time are as follows:

Reference: Bulletins 37, 64, 67. State Mineralogist Report II. Accounting for the production of gems in California is very 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 1914:

The value of the total gem production in California annually since the beginning of commercial production is as follows:

Reference: State Mineralogist Report XIII.

Graphite has been produced from time to time in the State, but it is difficult for these deposits, which are not particularly pure, to compete with foreign supplies which go on the market almost directly as they come from the deposit.

The annual graphite production of the United States amounts to about $250,000; the yearly imports have a value of approximately two million dollars. These facts show the possibilities which are open to this branch of the mineral industry provided, of course, that investigation would show sufficient amounts of high grade material to compete with the imported article, which at the present time comes largely from Ceylon. Low grade ores are concentrated with considerable difficulty and the electric process of manufacturing artificial graphite from coal has been perfected to such a degree that only deposits of natural graphite of a superior quality can be exploited with any certainty of

success.

On account of its unfusibility and resistance to the action of molten metals graphite is very valuable. It is also largely used in the manufacture of electrical appliances, of "lead" pencils, as a lubricant and in many other ways. Amorphous or "lump" graphite, commonly carrying many impurities, is worth as low as $10 a ton. For some purposes, such as foundry facings, etc., the low grade material is very satisfactory. The price increases with the grade of the material until the best quality crystalline variety, ranges as high as $200 per ton.

Occurrence of graphite has been reported at various times from Calaveras, Fresno, Los Angeles, Mendocino, San Bernardino, Siskiyou, Sonoma, and Tuolumne counties.

During 1914, no production was reported in this State. The previous production by years is as follows:

Gypsum is widely distributed throughout the State, and is produced to a considerable extent, to supply the fertilizer manufacturers and the manufacturers of plaster and cement. During 1914 the production by counties was as follows: