Mixtures for overlying or surface layers. 1. 40 parts magnesia. [Parts by weight.] 33 parts magnesium chloride solution, 19° Baumé. 10 parts asbestos powder. 5 parts wood flour. 1 part red ocher. (Sets in 24 hours.) 2. 25 parts magnesia. 25 parts magnesium chloride, 21° Baumé. 4 parts wood flour, impregnated with 43 parts Terpentinharzlösung. (Sets in 30 hours.) The magnesite used is, as explained, the fine ground calcined (not dead-burned) of certain specified kinds or place of derivation regularly sold for the plastic purposes. This material commonly comes in paper-lined casks, barrels, or boxes, in which form it is fairly permanent, but it deteriorates by exposure, absorbing carbonic acid and moisture from the air. If carefully handled it can probably be kept unopened a year or more, but it should be used within a few weeks after being opened, even under most favorable conditions. In considering mineral production the value of the crude material is used as far as practicable. Magnesite presents a peculiar example of a material which is seldom handled on the market in the crude state. It is calcined and ground before being considered marketable. The value of the calcined magnesite varies, the San Francisco price for 1914 averaging $25 to $30 per ton, which figure includes about $4 per ton freight. From two to two and one-half tons of the crude material are mined to make one ton of the calcined. From this derivation we have arbitrarily figured the value of the crude production, for 1914, on a basis of $10 per ton at the mine. Magnesite products have been found to be highly satisfactory and are growing in popularity, and the future for this industry appears to be bright. A large supply is already known to exist in California, and only a sufficient demand and cheaper transportation are lacking to make this an item of consequence in the mineral total of the State. Production for 1914, by county, is given in the following table, with total crude value, figured according to the foregoing assumption. In addition to this, a considerable tonnage was reported as having been mined at certain properties, but not marketed before the end of the year, hence not entered here: Annual production for California, amount and value, since 1887, is shown in the following tabulation: Reference: State Mineralogist Report XII. Marble is widely distributed in California. duction by counties was as follows: County In 1913, 41,654 cubic feet were sold, having a spot value of $113,282. The decrease from the previous year is doubtless a reflection of the laxity in building operations, which is shown by some of the other structural materials. Data on annual production since 1887, as compiled by the State Mining Bureau, follows. Previous to 1894 no records of amount were preserved: Reference: State Mineralogist Report XII. Bulletin 38. Onyx and travertine are known to exist in a number of places in California, but there has been no production reported since the year 1896. Reference: State Mineralogist Report XII. Bulletin 38. An unlimited amount of high grade sandstone is available in California, but the wide use of concrete in buildings of every character, as well as the popularity of a lighter colored building stone, has retarded this branch of the mineral industry very seriously during recent years. In 1914 six counties turned out 111,691 cubic feet, valued at $45,322, which is a considerable advance over the previous year. Production by counties is as follows: Amount and value, as far as contained in the records of this Bureau, are presented herewith, with total value from 1887 to date: 4-18655 |