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foreman at the mine at the time of the big cave in 1912, when a length of about 300 feet on the north end was lost, and he knew of good ore that had been left in the upper workings. The Heslep vertical shaft is about 50 feet south of the caved ground and is being used by Keyes. The stamp mill has been moved from the Patterson Mine near Tuttletown and 10 stamps have been erected and are in use, besides which two stamps are occasionally used.

Cost of mining and milling are low on account of the special conditions and the short distance ore is hoisted. Ore value at the same time is satisfactory, and will leave a very handsome margin of profit if the ore continues to mill as well as in October and November. Keyes states this ore shoot is about 260 feet long and six feet thick, and is in the Whitford vein which lies between the Heslep and Bull Quartz veins.

Hudson and Calhoun Pocket Mines near Sawmill Flat have made a small production of gold during the year.

Red Cross (Omega) Mine which was reopened for a short time during the summer has been closed down and is idle at the end of the year. Little more than unwatering and repair work was accomplished.

Some work has been done at the Spring Gulch Mine since July of this year. The shaft was cleaned out and repaired to the 200 ft. level, and crosscutting on this level is reported to have exposed a hitherto unexplored vein, which lies in the footwall of the Marshall vein, the one formerly worked. The operators planned to drift on this new vein. The mine is about five miles southeast of Tuolumne and was not visited.

A little work has also been done during the summer at Temescal Mine 2 miles from Confidence. Two men were employed.

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DRIFT MINES. Monarch Mine is near Confidence. Monarch Gravel Mining Co., Jerry Casey, secretary, 510 Page street, San Francisco. The company has kept at work since the 1920 report. There are now (Nov., 1923) 3500 feet of tunnel and crosscuts, mostly main tunnel. A shaft was sunk 135 feet deep on 25° incline at the face of the main tunnel and is reported to show coarse gravel. A winze level 100 feet below the main tunnel has also been run about 100 feet. A new shaft to furnish air and a second exit was being sunk in November to connect with the main tunnel. The gravel noted above as having been found below the main tunnel had not been prospected and nothing is known yet as to its extent.

Sledge Mine is about 4 miles by road from Confidence. The property has been prospected and worked in a small way for many years by the Sledge family but as far as could be learned without much output. It was drilled by puolumne Deep Channel Mining Company about 1913. A tunnel was also run 200 feet or more by former operators. The last company, which suspended work during the present year, is said to have spent about $35,000 on the property. Several new buildings were put up and the tunnel was extended to a total length of 600 feet.

Gravel shows in the face of the pit, near where the tunnel enters. The course of the tunnel turns west, northwest and north and strikes rim gravel near the face. This is apparently an intervolcanic channel, most of the sand and gravel being green with very little quartz. No work was done after striking the gravel. About a quarter of a mile

a ahead of the face of the tunnel presumably along the supposed course of the channel, a shaft had been started, but was nearly full of water at time of visit and had apparently not reached gravel, judging from the material on the dump. As no crosscutting nor drifting had been done in the gravel, the width, depth and direction could not be judged except by surface indications.

Springfield Tunnel and Development Company have continued to work their mine on a small scale. When the work had reached the old shaft where such a fine prospect had been found several years ago that they were led to great exertions and expense to reach it with a tunnel, it is reported the rich ground was found to be limited in extent, and they found mostly lower grade gravel surrounding it.

MARBLE.

Bell Marble Company, office address S. P. Building, San Francisco. The quarry at Columbia was being worked again in November after an idleness of six months. A crew of six men is employed. A Sullivan double channeling machine has been installed and a new 50-ton stiff leg derrick has been erected.

The market for marble is reported good but the demand is said to be principally for sawed slabs. The company is now selling stock to finance a marble sawing mill at West Berkeley. The Bell Marble Company has helped to build up a new industry in California raw material and has experienced the satisfaction of establishing the high quality of its product in competition with eastern and other marbles.

Columbia Marble Company continues the operation of its large marble quarry on the south side of the Stanislaus River canyon north of Columbia. This company has its own marble sawing mill and has been a steady producer for many years.

GRANITE. Sonora Granite Company has a quarry on the Rablen Ranch in Sec. 14, T. 1 N.; R. 15 E.; three miles from a shipping point on the Sierra Railway. J. E. Sasek, manager, Jamestown.

The stone is a pleasing dark granodiorite. They have brought in electric power to the quarry and have an air compressor, a few small buildings with accommodations for ten men, and some small tools. A few carloads of the stone have been shipped during the two years of desultory work, but the quarry has been idle since last July.

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MAGNESITE. The Gray Eagle Magnesite Mine near Chinese Camp has been taken over under lease by H. R. Vail and John P. Maxwell, 820 Syndicate Bldg., Oakland. When visited in November last, they were building a calcining plant (see photo) on the Sierra Railway at Chinese Camp

station. The kiln is of 15 tons calcined product daily. The ore is hauled from the mine, a distance of two miles, by motor trucks.

The vein is developed through an adit which crosscuts it at 310' in, thence a drift has been run 50'. This level is at a depth of 98' below the outcrop, and 34' below the upper drift, which was driven from the bottom of the shaft. In the stope the vein shows 8' to 10' in width. Mining of the ore is being done under a contract.

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Vail and Maxwell calcining plant at Chinese Camp, Tuolumne County, California, for

handling magnesite from the Gray Eagle Mine. Photo by Walter W. Bradley.

SAN FRANCISCO FIELD DIVISION.

C. McK. LAIZURE, Mining Engineer.

REVIEW OF ACTIVITIES IN 1923. During the past year the Redding field division office was discontinued and the former Auburn field division office moved to Sacramento. This change necessitated a redistricting of the State and some change in the counties assigned to the present three district offices at Sacramento, San Francisco and Los Angeles, respectively.

Del Norte, Humboldt and San Luis Obispo counties were added to the San Francisco field division, and Glenn, Colusa, Yolo, Sutter, Sacramento and Mono counties were placed in the new Sacramento district.

The net result was that Mariposa is now the only gold mining county of any importance in the San Francisco field division.

METAL MINING.

Mariposa County was not visited during 1923, but reports indicate that it has shared fully in the general revival noted in gold mining activities throughout the State, and that the outlook for continued improvement of conditions in 1924 is favorable.

The only other metal of importance produced in this district is quicksilver. Some interesting speculations regarding a possible increase in the use of quicksilver have developed since the reports of experiments with the Emmet mercury-steam boiler system have been made public in the technical press.

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An experimental installation of this system on a commercial scale was made by the General Electric Company in the plant of the Hartford Electric Light Company, Hartford, Conn., and its successful operation demonstrated. Theoretically, this system permits increased efficiency of about 100 per cent over steam alone. At the test installation the increase in output of electric power per pound of fuel was practically 50 per cent. With boilers especially adapted to the system and other refinements, it is expected that an increase in efficiency of 80 per cent over the present practice of steam-power plants will be reached.

Such a wonderful saving would lead to the conclusion that in a short time mercury will be used in all steam-power plants; however, the following figures will show that the world's production of quicksilver is far too small to meet such a demand.

According to the Engineering and Miring Journal-Press "the Emmet boiler at Hartford holds about 30.000 pounds of mercury. The total production of mercury in the United States in 1919 was 1,601,000 lb., enough to equip only fifty-three boilers like the one already equipped, which has developed about 1500 k.w. or nearly 2000 h.p. In 1922 the mercury produced in the United States had fallen to 478,000 lb., or enough to equip sixteen boilers of the size of the Emmet installation at Hartford. This United States production was, to be sure, only about one-fifth of the average production for nearly twenty years; nevertheless, it is clear that these twenty years have skimmed the cream from our deposits.

We have a tentative figure of the total amount of boiler horsepower used in the United States in the mining industries at 2,258,000 h.p., which, taking the amount of mercury required for the Hartford boiler, would require altogether nearly 34,000,000 lb. of quicksilver, which is more than the total amount of quicksilver produced in the United States in the last twenty-one years—1902 to 1922 inclusive. But the total amount for all purposes in the United States is 18,000,000 h.p., whose equipment would require 270,000,000 lb. of mercury!

The world production of mercury in 1921 was only 4,451,000 lb., enough to equip only 148 boilers of the size of the Hartford plant ! The total world's production for fourteen years from 1908 through 1921 inclusive was 110,337,000 lb., or less than half what would be required to change the high-pressure steam boilers of the United States alone to the mercury system.

As a further illustration of the revolutionary character of this system, it is said that the mercury used in the Hartford plant boiler cost about $16,000. This represents a considerable sum of money, but officials of the Hartford Electric Co. expect their coal bill to be cut in half by the installation of this boiler system, and their coal bill in 1922 was about $1,500,000, showing that they would save the cost of the mercury, at that price, in about eight days. Even with a much higher price for mercury, such an installation would prove economical in many cases. The mercury is used over and over again and need not be replaced.

Eng. & Min. Jour.- Press, Vol. 116, No. 25, page 1057, Dec. 22, 1923.

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It is quite evident from these figures that, if the demand for quicksilver for mercury-boiler power purposes grows, the lack of supply will send quicksilver prices soaring, and even this use in only a comparatively few boiler plants is likely to cause an immense increase in the price of the metal.

The principal producers in 1923 were the New Idria Quicksilver Mining Co., the New Almaden Co., Inc., and the Cloverdale mine of the Western Mercury Co. Mercury produced was about 75 per cent greater than the 1922 output.

Announcement has been made by Mr. Andrew Rocca, president of the Western Mercury Co., of the sale of the Cloverdale mine to H. W. Gould, et al.

The Helen mine, situated near Middletown, Lake County, has been purchased by Ludwig Graefe and A. Romaine.

A small production of manganese ore was recorded from San Joaquin and Stanislaus counties.

NON-METALLIC MINERALS. Although the mining of metals is limited, the mineral products of the twenty-five counties in this division approximates 25 to 30 million dollars annually, or twice the total gold production of the State. products are chiefly those minerals classified as fuels, structural materials, industrial materials and salines; and they include petroleum, natural gas, coal, brick and tile, cement, granite, lime, magnesite, sand and gravel, crushed rock and other miscellaneous stone, asbestos, pottery clay, dolomite, gems, gypsum, diatomaceous earth, limestone, mineral paint, mineral water, silica, sulphur, magnesium salts, potash, common salt and a few other minor minerals.

The mining and marketing of these products differ widely from metal mining in general and especially from gold mining. The gold producer has an unlimited market for his product at a fixed price of $20.67 per ounce, while the production of the structural and industrial minerals, fuels and salines is on a competitive basis. In the case of large mineral deposits of comparatively uniform composition, mining operations acquire many of the characteristics of a manufacturing industry. For aiding in the development of the mineral industry, reports upon the activities of going concerns of this character are of less value than are data on undeveloped deposits and new discoveries.

Fresno County, the principal mineral products of which are petroleum and natural gas, leads in value of production in this district. At the same time 'wildcat' drilling has continued more or less steadily in over half of the twenty-five counties, but to date no new commercial production has been established. That there are possible producing areas in this district, yet unproved, is unquestioned concerning both petroleum and natural gas.

Lively interest has been shown in the coal deposits of the State and development in this district has been carried on in Mendocino and San Benito counties, with additional activities probable in Contra Costa, Alameda and Monterey counties. A report upon the Eel River district in Mendocino County, where development work has been particularly active, was published in Report XIX of the State Mineralogist, Chapter IV, September 1923.

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