a depth of from eight to ten feet. As a result, in order to recover any of the gold, it was necessary to sluice off the entire bed rock until undecomposed material was reached. In California one of the best examples of primary concentration is in Holcomb Valley in San Bernardino County. Here a belt of mineralized porphyry extending in an easterly and westerly direction through Gold Mountain has been washed and concentrated along the sides of a comparatively shallow and wide basin. A third type of primary concentration is exhibited in Alaska in the vast terminal moraines of the Yukon River basin. The gravel as a whole is very spotted and irregular in gold content and is not commercially profitable. We now come to secondary concentrations, which probably represent the types of gravel commercially exploited in most of the placer mining districts of the present day. In the Sierras of California the system of Cretaceous rivers, which originally concentrated the gold from the metamorphic rocks thrown up by the Sierra uplift, have been crossed and recrossed at right angles by the present Quartenary system of drainage. As a result of this condition, the fabulously rich placers of the early days of California were formed. A single Quartenary stream in a bed not over fifty feet in width in many case represented the concentration of half a mile of Cretaceous stream bed. Often gravel carrying this gold had been disintegrated and worn by attrition so much that only two or three feet of material needed to be worked in order to obtain the product of thousands of billions of tons of country rock, which had been concentrated and reconcentrated for thousands and even millions of years. In Colombia, in Venzuela, the Guianas, and also in Ecuador, Peru and Bolivia, to a lesser degree these same conditions of secondary concentration have existed, but for some reason the primary concentrations seem to have produced the greater proportion of the placer gold that has been won from these countries. From the writer's observation, a reason for this is that the Cretaceous and Tertiary channels which have been concentrated by Quartenary streams in a manner analogous to California, have generally had their drainage through territory which was not auriferous. The transportation and deposition of placer gold are governed by laws which at first glance seem rather complicated, but in analysis of these principles we find that they are quite simple. Streams that are heavily loaded with sand and mud will naturally have greater transporting power than the streams that are clear, their velocity depending largely upon their grade and cross section, and as these two elements vary greatly at short distances in all mountain streams, it is natural that the amount of gold that the stream is capable of carrying at the bottom of its current will vary greatly, causing more or less irregular distribution. Often in the case of streams of intermittent flow of varying magnitude caused by changing conditions, there will be recurrent stratas of gravel, which contain alternate barren areas and concentrations of gold. During the volcanic period this condition was largely emphasized in the Sierras by the frequent showers of ash, mud and detrital material, which at frequent intervals blocked and choked the streams, causing them to abandon and resume certain definite courses at irregular intervals. As a rule, on the short turn of a river where the bed rock is sloping out toward a gentle curve and where the force of a current is lessened, we will find the greater concentrations of gold; conversely, on the long turns where the outside portion of the current moving at greater velocity has cut into bed rock, we do not find any great concentrations of gold because conditions have not been favorable for its lodging. Where a rib of hard bed rock crosses a stream, causing a change in its grade, gold does not generally lodge on the upstream side. The force of the current will drag it over the crest of the ridge and deposit it on the downstream slope. Pot holes in rivers that have any considerable grade, as a rule are absolutely barren. Small crevices, with their upper ends pointing upstream, if they run transverse to the direction of the current, will form natural riffles for heavy gold. As a rule, heavy gold does not travel very far from its source. Fine gold travels very readily. This is very clearly evidenced on the American River in California, especially on the middle fork. For many years the short turns and bars formed near the flood-line of the river have been worked and reworked by rockers year after year. The same condition existed at Posepny in Hungary, and notably so on the Snake River in Idaho. The concentration varies inversely as the distance from the source of the gold, whether primary or secondary. A river system is constantly working toward a grade or basal plane, which is continually being lowered. This tends to deposit values in fine gold lower and lower down the river. A case in point is noted in the deposition of the famous dredge placers of Oroville. Here the bed rock, however, is mostly tuffaceous, and it is quite possible that underneath this bed rock courses of the old Cretaceous rivers at great depth contained richer gravels than those that have been worked above. The difficulties in the way of prospecting and operating this material are such that it is extremely doubtful if it will ever be a commercial proposition to work. Prospecting an area like this is too much like operating a punch-board-the amount of money put in is apt to be considerably more than the result is worth. In general, it may be said that coarse gold as a rule is associated with gravel that contains the heavier constituents of the original rock; whereas fine gold is often and even generally associated with sand, clay, and light material. A case in point was noted by the writer on Portage Creek on the upper reaches of the Little Delta River in Alaska. Portage Creek drains the area of glacial moraines in the basin of the upper Tanana for an area of perhaps 50 square miles. There is no bed rock visible and the stream basins are all in gravel. At the bottom of the Portage Creek drainage there is a streak about six inches in depth lying on what may be termed "an original gravel bed rock," which carries a small amount of heavy gold. Above this streak there are four or five feet of light sand and pebbles. One or two fine colors to the pan is the average run of the upper gravel. SECRETARY'S OFFICE. W. W. THAYER, Secretary. The California State Mining Bureau was created April 16, 1880, by legislative act. In March, 1893, the original act was repealed and an amended act approved and passed by the legislative body. Again on June 16, 1913, a new Mining Bureau Act was approved which became effective August 10, 1913, repealing all former acts, and forming the basic law under which the Bureau now functions. It is doubtless true that both the mining and lay public have not in the past always recognized the part played by the Bureau in the development of the state's mineral resources. Innumerable inquiries regarding them, originating within and without its borders and in foreign countries, have been answered with ultimate results reflected by a consistent growth in the value of the state's mineral output since the records of production were first compiled by the Bureau in 1887. It is believed that a better understanding of the economic position occupied by the Bureau will be imparted to the public, whose funds support it, by embodying in the Monthly Chapter a review of the executive activities. The responsibility for the coordination of effort of each department, to the end that the utmost efficiency may be maintained with the limited and variable appropriations accorded the Bureau by successive legislatures, rests upon the office of Secretary. Activities referable to that office, such as reports of new maps and publications issued, amount of mail handled, changes and enlargements in offices, changes in personnel of the staff, property and equipment, financial statements, etc., are therefore included herein. New Publications. During the month the following Bureau Publications have been made available for distribution: Summary of Operations, California Oil Fields, October, 1922, Vol. 8, No. 4. Mining in California, October, 1922, Vol. 18, No. 10. Distribution of Publications. The Bureau's publications are constantly in demand, requests for copies coming from all over the United States and foreign countries. Publications were distributed during the month as follows: Publications Mines and Mineral Resources of San Bernardino, etc. Mines and Mineral Resources of Nevada County Mines and Mineral Resources of Sierra County Bulletin No. 6, California Gold Mill Practices_. Number distributed Bulletin No. 37, Gems, Jewelers' Materials, Ornamental Stones of California Bulletin No. 72, Geologic Formations of California__. Bulletin No. 75, United States and California Mining Laws_ Bulletin No. 76, Manganese and Chromium in California_. 2 1 10 Bulletin No. 89, Petroleum Resources of California, with special reference Bulletin No. 90, California Mineral Production for 1920, with County Maps 61 50 3000 50 -3000 2 6 2 15 2 470 38 The Bureau maintains in addition to its correspondence file a mine report file which includes reports on some 7500 mines and mineral properties in California. Also there is available to the public a file of the permits granted to mining and oil corporations by the State Commissioner of Corporations. During the month 768 letters were received and answered. They are practically all requests for information and the inquiries cover all phases of prospecting, mining and developing mineral deposits, reduction of crude minerals and marketing of refined products. Drafting. The Bureau maintains an up-to-date drafting department, where topographic and geological maps, tracings, oil well logs, and oil field maps are prepared. DIVISION OF MINERALS AND STATISTICS. WALTER W. BRADLEY, Statistician and Curator. Estimate of 1922 Output. STATISTICS. The total value of the mineral production of California for the year 1922, just closed, is conservatively estimated to have been approximately $257,351,690. This is, in part, detailed in the tabulation below; but, as there are more than fifty mineral substances on California's commercial list, it is impractical at this early date to obtain definite figures on other than the more important items. The blank report forms have been mailed out to the operators in all mineral lines, and the date of publication of the final and complete report will depend upon the promptness of their replies. The State Mining Bureau urges the hearty cooperation of all concerned, to the end that the results may be made known early. This estimated total of $257,351,690 is a decrease of $10,805,782 from the 1921 production, due mainly to lower prices prevailing for crude petroleum, and an apparent decrease of nearly a million dollars in the gold yield. Preliminary reports indicate a record yield of approximately 139,000,000 barrels of petroleum; but, as production was considerably in excess of consumption, the prices for all grades dropped accordingly. This resulted in lowering the average price, although the increased yield was of the higher-gravity oils and especially in the later part of the year. We have estimated an average value, at the well, of $1.60 per barrel for the first six months of 1922, and $1.21 per barrel, the second half; the amounts being 61,000,000 barrels and 78,000,000 barrels, respectively, for the two periods. This gives an average of $1.375 per barrel for 1922 as against $1.804 per barrel in 1921. This results in a net decrease of slightly over $12,000,000 in total value. Though reports from the gold mining districts have, for the most part, been indicative of renewed interest and renewing operations, receipts of bullion at the mint and smelters show a decrease for the year. This was in part due to the Argonaut mine fire, and to a slight decrease in dredge yield. Silver, mainly from the Randsburg district as in 1921, showed a small decrease from the high point of the preceding year. Copper shows an increase to nearly double the 1921 figure, owing to the resumption of shipments by the Walker mine in Plumas County and the continuity of operations by its neighbor, the Engels group. Lead and zinc increased materially, both in quantity and value; as did also quicksilver in a lesser degree. Magnesite shipments increased about 25 per cent, owing to improvement in the demand for plastic purposes. As the demand for building materials was active during 1922, the structural group (brick, cement, building stone, crushed rock, etc.) showed some increase in value over 1921. There were no notable changes in the general status of the miscellaneous "industrial" group; nor among the salines, except horax. The last-named recovered, in part, from the slump of 1921, and the present market is reported favorable for a continuation of activity. |