I" "W l i^iWi ^ ^ 11 ■iwtvu.^^w MmmmmMmmm nw—ro > «i i i «« w « MAGNESITE IN CALIFORNIA BULLETIN No. 79 ]$S>m.O iJY THE CALIFORNIA STATE MINING BUREAl FERRY BUILDING, SAN FRANQSCO mmmmmmm iaM%af^*«i#*wi»Mwwppo— aM»— m» x>iw>ai*^iwW M«y I92& nt^^fn^mfifMt^m^ m mfmnmmmmmn M— il W B WH Mll «> ■ KOWMimiB— Wll IIIIBM « I > THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA DAVIS F. S. D-" P*»0 K I V e D I NOV 2 5 1925 LIBRARY CALIFORNIA STATE MINING BUREAU FERRY BUILDING, SAN FRANCISCO LLOYD L. ROOT State Mineralogist San Francisco] BULLETIN No. 79 [May, 1925 MAGNESITE IN CALIFORNIA By WALTER W. BRADLEY CALIFORNIA STATE I'RINriNG OFFICE JOHN E. KING, State Printer SACRAMKNTO, 1925 LIBRARY UNIVERSITY OF CALIFORNIA DAVIS CONTENTS. Page LETTER OF TRANSMITTAL 7 TREFACE 8 INTRODUCTION 9 Properties and Origin 10 Industrial Applications and Uses 13 Testing and Specifications for Magnesium Oxychloride Cements 21 Production and Prices 33 Tariff avd Importations 38 Bibliography 39 CALIFORNIAN MINES AND PLANTS 41 Alameda County 41 Fresno County 44 Kern County 47 Kings County 51 Los Angeles County 52 Mendocino County 52 Merced County 52 Monterey County 53 Napa County 53 Nevada County 58 Placer County 59 Riverside County 61 San Benito County 66 San Bernardino County 72 San Diego County _- 76 San Luis Obispo County 7fi Santa Barbara County 77 Santa Clara County 78 Sonoma County 89 Stanislaus County 98 Tulare County 103 Tuolumne County 138 94580 ILLUSTRATIONS. PHOTOGRAPHS. Page 1. Magnesite specimen showing conchoidal fracture. From No. 4 Tunnel, Tulare mine of Sierra Magnesite Company, near Success, Tulare County 10 2. Magnesite specimen showing conchoidal fracture. From Stanislaus County__ 10 3. Magnesite from Rolling deposit near Preston, Sonoma County, California, showing shrinlcage cracks 12 4. Magnesite from Kolling deposit, Sonoma County, showing pitted surface due to weathering 14 5. Magnesite from Sonoma Magnesite Company's mine Sonoma County, showing parallel shrinlcage cracks 14 C. Cedar Mountain magnesite mine, Alameda County 40 7. Open cut (glory hole) in Cedar Mountain magnesite mine 40 S. Flat-hearth calcining furnace, at Cedar Mountain magnesite mine 42 9. Pellets of hydro-magnesite in serpentine in Sec. 34, T. 4 S., R. 3 B., M. D. M., Alameda County 43 10. Magnesite calcining furnace of Sinclair Bros. (Ferguson), at Piedra, Fresno County 45 11. General view of Bissell magnesite mine, looking eastward 47 12. Bissell magnesite deposit, showing stratification, also folding and faulting 48 13. Bissell magnesite deposit, showing stratification, also dip to south 49 14. Scott fine-ore quicksilver furnace at Kings mine. Kings County, used for calcining magnesite 51 15. Calcining plant at Maltby No. 2 mine. Chiles Valley, Napa County. Producing dead-burned magnesite in a rotary kiln 54 IC. White Rock mine in Pope Valley, Napa County 57 17. Calcining plant at White Rock mine. Pope Valley, Napa County 58 18. Stockwork of magnesite veins in open-cut at Hemet magnesite mine. Riverside County 61 19. General view of Hemet magnesite mine, looking westward from top of hill across Hemet Valley, Riverside County 63 20. Hemet magnesite mine, looking eastward, showing dumps and plant 63 21. Outcrop of magnesite at Sampson magnesite mine, San Benito County 64 22. South open-cut at Sampson magnesite mine, Oct. 2, 1917, before installation of aerial tram 66 23. Quarries and ore-bins of Sampson magnesite mine, taken from aerial tram, November 8, 1923 — -- 67 24. Main open-cut at Sampson (Maltby No. 3) magnesite mine, near New Idria, San Benito County, November, 1923 07 25. Calcining magnesite in vertical kilns, at Sampson mine, October, 1917 68 26. Interior of vertical, magnesite-calcining furnace of Hoff-Price Company at Sampson mine, under construction Oct. 2, 1917 69 27. Calcining plant at Maltby No. 3 (Sampson) magnesite mine, producing dead- burned refractory magnesite, November, 1923 69 ILLUSTRATIONS. 5 Page 28. Rotary kiln at Maltby No. 3 (Sampson) magnesite mine, San Benito County— 70 29. Magnesite outcrop on the ClifEside claim, near Afton, San Bernardino County_ 73 30. Afton magnesite deposit, showing outcrop on the Hill Top claim 73 31. Magnesite exposure on the Quaker Group, southeast of Cima, San Bernardino County '^4 32. Plant of International Magnesite Company (now Duralite Company), at Chula "Vista, San Diego County 76 33. Open-cut of "^''estern Magnesite Development Company (in 1915) 83 34. Plant and mines of \A'estern Magnesite Development Company (Maltby No. 1), looking easterly 84 35. South end (White Queen) workings at Maltby No. 1 mine 86 36. Tramming ore from north end of White Diamond workings, at Maltby No. 1 mine (Western Magnesite Development Company) on Red Mountain 87 37. Vertical kiln of Western Magnesite Development Company 88 38. Scott, fine-ore, quicksilver furnace in use for calcining magnesite fines at Maltby No. 1 mine 88 39. Kiln of the Refractory Magnesite Company, east of Preston, Sonoma County_ 90 40. Vein of magnesite as exposed in an open-cut on the Alfred Claim of the Sonoma Magnesite Company, Sonoma County 93 4). Ore chute at upper deposit of Sonoma Magnesite Company 94 4-. Rotary kiln of Sonoma Magnesite Company, at Magnesite, Sonoma County 95 43. Magnesite calcining furnace of the Western Carbonic Acid Oas Company, at Guerneville, Sonoma County 96 44. Mines of Oustine Magnesite Company (left) and Howard Cattle Company (right), in Stanislaus County west of Ingomar 100 4.">. Magnesite loading-bunkers at Ingomar. for the Gustine magnesite and Howard Cattlf Company mines 101 4t). Magnesite vein 3 feet thick, in No. 3 workings of Lindsay mine, near Success, Tulare County 103 4 7. Slickenside magnesite, showing effect of movement along the vein, in tunnel of Lindsay Mining Company 105 48. View northward showing blanket veins being worked on the property of the Porterville Magnesite Company in 1917 110 49. Southerly side of 'north' hill (Harker mine) from the south, showing both 'gash' and 'blanket' veins 112 50. North end of 'north' hill of Harker mine. Portion of 'Oakland' mine of Sierra Magnesite Company in foreground 114 51. Calcining plant at Harker mine (Porterville Magnesite Company), near Porterville, Tulare County 116 52. Sierra Magnesite Company's properties on South Fork of Tule River, near Success, Tulare County 120 53. Vertical kilns of the Tulare Mining Company (now Sierra Magnesite), at Magnesite Station, Tulare County 121 54. Ore dumps, at 'A-South' opening. Sierra Magnesite Company 122 55. Stockwork of veins at 'Lower' quarry on Sierra 'Standard' workings 126 6 ILIiUSTRATIONS. Page 5fi. Stoikwork of veins in No. fl Quarry ('South Summit Quarry") at Sierra 'Standard' workings 127 57. Sloping vein in No. 22 Tunnel, 'Oakland' ground of Sierra Magnesite Company 128 58. Calcining plant of Sierra Magnesite Company at Porterville, Tulare County 130 59. Rotary kilns of the Sierra Magnesite Company at Porterville 131 60. Cooling floor, Sierra Magnesite Company, Porterville 134 61. Two banks containing 12 buhr mills, Sierra Magnesite Company, Porterville 136 62. Vail and Maxwell calcining plant at Chinese Camp, Tuolumne County, for handling magnesite from the Gray Eagle mine 138 PLATES. I. Outline map of California showing location of magnesite deposits 10 II. Cross-bending testing machine 32 III. Berry strain gauge 33 /^ IV. Chart showing production and average value of magnesite in California, 1887-1924 (inc.) 36 V. Sketch showing approximate section through Bissell magnesite deposit 48 VI. Sketch map and vertical section of Afton Magnesite Group, San Bernardino County 72 VII. Sketch map of magnesite deposits on Red Mountain, Santa Clara County 82 VIII. Map showing claims and workings of the Western Magnesite Development Company (Maltby No. 1 mine), on Red Mountain, Santa Clara County_ 82 IX. Map of White Diamond (north end) workings of Maltby No. 1 mine 84 X. Map showing locations of magnesite deposits in the vicinity of Porterville, Tulare County, California 104 XI. Flow-sheet of magnesite plant of the Sierra Magnesite Company at Porterville 132 LETTER OF TRANSMITTAL. June 15, 1925. To His Excellency, The Honorable Friend Wm. Richardson, Governor of the State of California. Sir: 1 have the honor to lierevvith transmit Bulletin No. 79 of the State ]\Iining Bureau, on Magnesite in California. This work deals in detail with one of California's very important non-metallic mineral resources. California was for many years the sole domestic producer of magnesite in the United States, and still leads. The commercial uses for magnesite are expanding and daily increasing in importance; so that there is now an active demand for such data and information as this bulletin makes available to the public. Respectfully submitted. Lloyd L. Root, State Mineralogist. PREFACE. Originally the manuscript for this bulletin on California's magne- site resources was prepared following a special field survey made by the staff of the State Mining Bureau during the spring and summer of 1917. There was an acute demand for domestic magnesite at that time due to the situation brought about by the war in Europe. Besides the present author, the Bureau's engineers participating in that sur- vey Avere : Messrs. Clarence A. Waring, Emile Huguenin, W. Burling Tucker, and Clyde McK. Laizure. Lack of available funds for print- ing prevented publication at that time. Late in 1918 the manuscript was revised, mainly by Mr. Waring (since deceased), and again pre- pared for publication, but again it was held up for lack of printing funds. With the resumption of foreign importations shortly after the close of hostilities in Europe, there was a sharp break in the domestic production of magnesite. Following the placing of a moderate customs duty, coupled with the expanding growth of the plastic trade, the situation has improved materially for the domestic producers of magnesite, particularly in California. There is a healthy demand for the Californian mineral because of its adaptability for plastic purposes. For this reason, the present author has recently made a resurvey of the more important districts in the state, bringing up to date the various changes in ownership and plant installations, and adding notes relative to certain new discoveries. The data relative to Placer County were verified in 1924 by Mr. C. A. Logan, district engineer of the Bureau at Sacramento ; and the data on Kiverside and San Bernardino counties verified by Mr. W. Burling Tucker, district engineer at Los Angeles. New data on standardization, specifications, and testing prac- tices are also included. Walter W. Bradley. San Francisco, May 15, 1925. INTRODUCTION. Magnesite is known to tlie iivnin-al public solely as a structural and industrial material. It has been exploited and utilized for such pur- poses for many years, during which time it has earned an enviable reputation and reached an important position among mineral products. Strictly speaking, magnesite is also an ore of the metal magnesium, but as such it has never shared in the common knowledge which the public has of ores of the better known metals, nor enjoyed the universal interest which metallic minerals usually excite. For this reason, although magnesite is neither unusual nor rare, it can hardly l)e said to be a conunon mineral. It is interesting to note that, in the United States, deposits of connuercial size are as yet unknown outside of Cali- fornia and Washington. Extensive deposits of exceptionally high-grade magnesite have been knoAvn for many years to exist in California. An early list of the known deposits i)ublished in the Sixth Annual Report of the State ^lineralogist.^ included occurrences in no less than nine counties. Altliough there was no commercial production from these deposits at the time, their potential value to the state was clearly recognized. Actual production began a little later, in 1886,- with the shipment of a small tonnage from Cedar Mountain in Alameda County; but the exact figures are not recorded. In commenting on the presence of magnesite. among other things, the Hanks report said: "The Cali- fornia mineral will be turned to account at some future time, when it will be interesting and important to know where it may be found.'' The magnesite industry today witnesses the fulfillment of that prophecy. Conditions governing the production and consumption of domestic magnesite have been such, however, that there Avas comparatively little actual realization from these valuable natural assets until changes brought on by the European war made it possible to fully develop and exploit the state's resources in this important mineral. Before the war nearly all the magnesite used for refractory pur- poses in the I'^nited States was imported. It was used as linings for basic steel furnaces and converters, and in other melting and heating furnaces in metallurgical works. The principal market for refractories was (and still is) in the eastern steel centers; and cheap foreign labor and low ocean freight rates gave foreign magnesite a commercial advantage over that produced in the west. According to Gale ^ "In 1912 the quantity of crude and calcined magnesite imported * * * ^r.^ * * * 20 times the domestic production. ' ' Domestic, in this instance, means California ; for up to the end of 1916 California was the only state of record in the United States, producing magnesite in commercial quantities. In fact, there was no production outside the state on the North American Continent. The Washington deposits became a factor in supplying the refractories market, in 1917. 'Hanks. H. C,., Sixth annual report of the State Mineralogist: Cal. State Min. Bur., Report VI. Part I, p. 119, 1886. = U. ,S. Geol. Surv., Mineral Resources of the U. S., 1886, pp. 6, 696, 1887. ' Gale, H. S., Magnesite dti)0sits in California and Nevada : U. S. Geol. Surv. Bull. 540, page 484, 1914. 10 CALIFORNIA STATE TVIININO BUREAU. Photo No. 1 — Magnesite specimen showing- conchoidal fracture. From No. 4 Tunnel, Tulare Mine of Sierra Magnesite Company, near Success, Tulare County. TAvo-thirds natural size. Photo No. 2 — Magnesite Specimen showing conchoidal fracture. From Stanislaus County. Two-thirds natural size. CALl FORNIA STATE M!\'ING BUREAU- L1.0YD L. ROOT STATE MIHEWCCCIST OUTLINLMAP 5 I S K I Y U I ^^ I TZl T E H AMA( p LU MAS | / 1 9o».«t • locmo :. tlj-L/""""'; -■-;) ^.^.^.^j 5ANrflANCiscoS\o..;;:C»'' ^";'..„.„ C "~ y ^^ /i^ CAUrORNL\ SHOWING LOCATIONS M\GNESITE DEPOSITS MAY, 1925. ACC0MRANYIN5 BULLETIN N?79 s"^, SAN v*""-o_r INYO \ <-> MONTEREY^- J^ /'•"'"•(' 't a LA RE \^ '' >"\!^] ^ r:^\. N BER'NAROINO R 5 1 D E^ MEXICO J MAGNESITE IN CALIFORNIA. 11 Although the output of ('alifornia liad o-rowii from a beginning in 1887 of 600 tons, to an average of a])0ut 10,000 tons of crude per year between 1908 and 1914 inclusive, the entire production was practically all consumed on the Pacific Coast, the greater portion being utilized in the 'sulphite proce\ss' of manufacturing wood-pulp paper. The disruption of shipping and cutting off of foreign supplies, due to the war, soon made it necessary for eastern consumers to depend largely on domestic sources for magnesite, and to offer much higher prices than formerly prevailed. The stimulating effect of heavy demand and high prices began to be felt by the magnesite industry of the state late in 1914. The production in 1915 was more than double that of the previous year, and a large percentage of the mineral was shipped east to be used for refractory purposes. Increasing prices, as foreign material became still more scarce in the market, led to sub- stantial capital investment in magnesite properties. Many new deposits were developed, old ones were reopened and new and larger calcining plants were constructed, at various points in the state. The expan- sion of the industry was remarkable. The 1916 production of magne- site showed a 5-fold increase over that of 1915, and reached a value of 11 million dollars. Mining activities in 1917 were marked by a slower but healthy growth. The increase in tonnage approximated 33';^ , and the total value of the crude closely approached 2 million dollars. At the present time, though the principal consumption of Cahfornian magnesite is west of the Mississippi River, there is some tonnage going to the Atlantic seaboard, via the Panama Canal. Magnesite has widely divergent applications in the industrial arts. These are not entirely distinct but they may be roughly divided into i-efractory uses, plastic uses, and chemical or miscellaneous. It was the absolute necessity for suitable refractory materials, in connection with the manufacture of steel and in other metallurgical processes, that made the domestic production of this mineral of such prime importance to the nation during the \var period. Chas. G. Yale ^ says : "Were an the known deposits in California brought to their capacity of pro- auction, It would l)e difficult for them to furnish the magnesite needed' annually the United Mates for refractory purposes. They could easily meet, how- ever, both in quantitiy and quality, the domestic demand for the purer grades of othfr^produ"^tl " l^^^l^^r, cement, paints, fireproof and damp-proof coalings, and The latter uses were, of course, subordinate while the war lasted to those affecting the output of steel and the efficiency of other war industries; but many magnesite products which were developed, and are being developed, by peaceful competition, have been found extremely well adapted to the ])urposes for which intended, so that on the whole It may be safely said, that in its large and varied field of usefulness magnesite has no substitute. PROPERTIES AND ORIGIN. Magnesite is a mineral of simple composition, it being e.ssentiallv a magnesium carbonate (MgCO,), eciuivalent to magnesium oxide, called 'magnesia,' (MgO) -f carbon dioxide (COJ. Limestone, the massive form of the mineral calcite, is a calcium carbonate (CaCO,) composed of calcium oxide, called 'lime' (CaO) + carbon dioxide (CO2). ' U. S. Geol. Surv. : Min. Res. of the U. S. 1915, Part II, page 1020. 12 CALIFORNIA STATE MINING BUREAU. From the above it will be seen that the two minerals calcite and magnesite are closely related chemically. Limestone (calcite) when heated, gives off the gas CO,, and lime or calcium oxide remains, the metallic base of which is the element calcium. Similarly magnesite when heated gives off CO2 and magnesia or magnesium oxide remains. Its base is the metal magnesium. Pure magnesite contains 47.6% magnesia (MgO) and 52.4% carbon dioxide (COJ. Calcium and magnesium are inter-replacable, one with the other, in all proportions, in these carbonates ; and when the chemical combination is in equal proportions, we have the mineral, dolomite, (CaMg)C03. Magnesite usually occurs as a white, compact, fine-grained, ma.ssive mineral. Its color may vary, according to the degree of purity, to yellowish or grayish, white and brown. Crystalline structure is rare, Photo No. 3 — Magnesite from Kolling deposit near Preston, Sonoma County, sliowing slirinliage cracks. Two-thirds natural size. except in Austria and Washington. Impure varieties are sometimes coarsely granular or earthy. When earthy it is often mixed with hydrated silicate of magnesia (sepiolite, or meerschaum) ; in fact, early mineralogists at first considered meerschaum to be a siliceous variety of magnesite. The common massive form has a dull luster, hardness of from 3.5 to 4.5 and shows a smooth conchoidal fracture resembling unglazed porcelain. (See Photos 1 and 2.) If cold dilute hydrochloric acid (HCl) be dropped upon it no action takes place, but hot acid will cause effervescence. Various proportions of silica, alumina, lime and iron oxides are often present as impurities. Bodies of magnesite of workable size according to Eckel ^ "occur commonly in one of three associations the methods of origin of the deposits being different in each case. The three types of deposits are : » Eckel, E. C, Cements, Limes and Plasters, p. 149, 1905. MAGNESITE IN CALIFORNIA. 13 1. Magnesite occurs most commonly in the form of irregular veins or pockets in serpentine or other magnesian igneous rocks.' In this case the magnesite has been formed as a decomposition product arising from the decay of the igneous rocks. 2. Magnesite occurs in the form of beds associated with deposits of rock salt, gypsum, etc. In this case the magnesite deposit has undoubtedly originated by direct deposition of magnesium carbonate from bodies of concentrated saline waters. 3. Magnesite also occurs in the form of beds interstratified with shales, limestones, etc. Magnesite deposits of this type are commonly ascribed to the replacement of the lime (in a limestone) by magnesia carried in by percolating waters. This may be true in some cases, but such deposits may also have originated by direct deposition, as described under (2) above." Gale/ referring to thef magnesite deposits of California and Nevada, says : "Most of the deposits of magnesite known are associated with intrusive igneous rocks such as peridotite and allied basic rocks, which are composed essentially of minerals rich in magnesia, like olivine and the pyroxenes. As the magnesite occurs in veins and lodes, in part replacing the igneous rock, it seems quite clear that it is derived mainly from the alteration of the intrusive magnesian rock. In the original rock the magnesia is present principally in the form of silicates. By alteration of the silicates to the carbonate, magnesite, the silica is set free. The magnesite veins commonly occur in zones of more intensive alteration in the magnesian silicate country rocks, and these zones are most conspicuously charac- terized by secondary silica, as opal, chalcedony, or quartz. One of the most common products of the decomposition by hydration or weathering of magnesia-rich silicate rocks is the green mineral serpentine, a magnesian silicate, with water in combination, and this alteration takes place so extensively over the surface areas of the basic intrusive rocks here described that the whole mass is commonly referred to as 'serpentine', although that term strictly signifies a specific mineral rather than a rock that is more or less diverse in composition." INDUSTRIAL USES. Magnesite is identified with a large and growing variety of industrial nses. Its leading applications are summarized as follows : 1. For refraetoiy purposes, as fire brick or in monolithic form for metallurgical furnace and converter linings, furnace hearths, cru- cibles, etc. 2. Plastic purposes. Calcined and ground for oxychloride or Sorel cement. 3. In the manufacture of wood-pulp paper. 4. For making carbonic acid gas. 5. Both crude and calcined, for heat insulation and miscellaneous applications. 6. For making refined magnesia salts. 7. As a source of the metal magnesium. Refractory Products. The use of magnesite for refractory purposes is undoubtedly its most important application, at least at present, so far as tonnage require- ments are concerned. Infusible, dense, chemically-stable magnesia is produced when crude magnesite is subjected to complete calcination. This material is used for the lining of basic open-hearth steel furnaces, for furnace hearths, crucibles, cupels, etc. It is also employed in copper reverberatories and other special metallurgical furnaces such as for handling bullion ; silver slimes; electric smelting; heating; welding and melting furnaces; calcium carbide kilns; and in the burning zone of rotary kilns in Portland cement plants. For these purposes it is made into magnesia brick or the material is rammed into place or plastered on, much as concrete is, forming a one-piece lining or surface. 'Gale, H. S., Magnesite deposits in California and Nevada: U. S. Geol. Surv Bull. 540, page 486, 1914. 14 CALIFORNIA STATE MINING BUREAU, Photo No. 4 — Magnesite from Kolling deposit, Sonoma County, showing pitted surface due to weathering. Two-thirds natural size. Photo No. 5 — Magnesite from Sonoma Magnesite Com- pany's mine, Sonoma County, showing parallel shrink- age cracks. Two-thirds natural size. MAGNESITE IN CALIFORNIA. 15 Crude magnesite is calcined or burned, sometimes Avith coke, in vertical-stack kilns, or in the more modern horizontal rotary oil-fired kiln. In California, many stack kilns are also oil fired. The prop- erties of the calcined pi'oduct vary with the temperature employed and length of time of burning. Light-burned magnesite has a specific gravity of 3.00 to 8.07 ; it will slake with water and then if exposed to the air will partly reearbonate and harden slowly, as lime does. It has considerable plasticity and may be moulded under pressure into various shapes. However, if calcination is carried on at a higher temperature or for a longer period a 'dead burned' magnesia, having a specific gravity of 3.61 to 3.80, is produced. When dead burned, magnesite Avill not take up either water or carbon dioxide from the air ; furthermore it possesses no plasticity. Refractory magnesia bricks and furnace linings are made from a mixture of the two forms in the proportion of 4 to 6 parts of the heavy to 1 of the light. The dense inert magnesia furnishes the base while the lighter form gives the mi.xture plasticity and causes it to harden. Although commonly believed that the 'dead burned' product derived from magnesite containing little or no lime, silica, oxide of iron, or alumina, is the most refractory, the imported material formerly used with satisfactory results, contained from 3% to 4% of silica, 6% to 8% iron and up to 4% of lime. It is even reported^ that "Some of the California magnesite which is very pure and without iron is mixed with 10% of slag from steel furnaces before being used for furnace linings." The following official analyses of magnesite from properties in vari- ous counties which appeared in a press bulletin - of the U. S. Geological Survey clearly show the characteristic, low-iron content of the Californiau material. Analyses of crude and calcined magnesite from California. [Chase Palmer, analyst.] 1 2 3456 78 SiOo 1.94 2.43 2.26 4.35 12.65 13.88 2.57 14.72 FeO 1.49 2.40 2.11 1.71 .80 1.49 .89 1.35 CaO .67 1.57 1.52 2.11 .95 .27 .80 .64 MgO 45.01 43.62 44.10 42.62 40.73 39.60 45.65 39.60 COo 50.65 50.11 50.18 49.05 44.64 44.62 50.33 43.73 99.76 100.13 100.17 99.84 99.77 99.86 100.24 100.04 9 10 11 12 13" 14 15 16» SiOo 8.73 9.57 1.82 0.50 0.50 2.70 1 67 0.51 FeO .97 1.00 .50 .20 ".43 .23 .31 b.57 CaO .39 2.83 1.85 1.92 4.90 .80 1.17 2.48 MgO ___ 43.18 42.48 45.12 45.90 83.17 46.02 45 75 90.30 CO. 46.31 44.70 50.73 51.68 11.34 50.32 50.95 5.22 99.58 100.58 100.02 100.20 100.34 100.07 99.85 99.08 17 18 19 20 21 22 « SiOi 12.05 2.40 0.65 6.37 1.10 5 21 FeO 2.83 1.44 .33 .35 .72 "1.70 ^i^9, l-S** -"J-eS 2.65 2.88 1.17 2.18 MgO 38.88 42.56 45.43 41.55 45.64 89.08 CO. 44.84 49.94 51.42 49.18 51.20 1.65 100.58 100.02 100.48 100.33 39.83 99.82 ;^ U. S. Geol. Survey: Min. Res. of the U. S. 1915, Part II, page 1024. - U. &. Geol. Surv: Press Bulletin No. 377, August, 1918. * Calcined. " Fe^Oj. 16 CALIFORNIA STATE MINING BUREAU. "t. White Rock mine, bunker, Pope Valley, Napa County, Cal. 2. White Rock mine, east vein, stock pile, Pope Valley, Napa County, Cal. 3. White Rock mine, upper tunnel. Pope Valley, Napa County, Cal. 4. Tulare Mining Co., Blanco mine, stock pile. Chiles Valley, Napa County, Cal. 5. Soda Creek mine, Detert & Elder, south tunnel, stock pile, Soda Valley, Napa County, Cal. 6. Soda Creek mine, north tunnel, stock pile. 7. Harker quarry, stock pile, Gilliam Creek, Sonoma County, Cal. 8. Sonoma Magnesite Co., lower mine, stock pile, Austin Creek, Sonoma County, Cal. 9. Sonoma Magnesite Co., upper mine, stock pile. 10 Cedar Mountain mine, Clark & McDonald, sacked for shipping, Alameda County, Cal. 11. Western Magnesite Development Co., White Queen mine, 250 feet inside tunnel, Red Mountain, Santa Clara County, Cal. 12. White Queen mine, stock pile. 13. White Queen mine, kilns. 14 Pacific mine, bunker, Red Mountain, Santa Clara County, Cal. is! Red Mountain Magnesite Co., Butcher mine, bunker. Red Mountain, Stanislaus County, Cal. IG. Butcher mine, cooling bins. 17. McLaughlin mine, stock pile on loading platform, Bradford ranch, Evergreen, Santa Clara County, Cal. 18. Jackson mine, stock pile, Cochrane ranch, Morgan Hill, Santa Clara County, Cal. 19. Warwick mine, lower cut, stock pile, Madrone, Santa Clara County. 20. Warwick mine, upper cut, stock pile. 21. Hoff-Price Co. mine, stock pile, Sampson Peak, San Benito County, Cal. 22. Hoff-Price Co. mine, cooling floor." It further says : "Of all the California magnesite here shown, that of the White Rock Mine (Nos. 1, 2, 3), Napa County, Cal., is highest in iron content and at the same time reasonably low in silica and lime. Material from two small properties (Nos. 17-18) in Santa Clara County carries as much iron, but one is high in silica and the other is high in lime. The White Rock Mine is supplying much of the calcined magnesite used by steel mills on the Pacific coast. Some of the California Magnesite that is very high in silica is used for plastic purposes and is said to be satisfactory." In general, for smelter use the calcined magnesite should not contain over 8% CaO, and it must have a minimum of 85% MgO and less than 8% Si02 or 5% sesquioxide (Fe, Al, and Mn), but these percent- ages are, of course, subject to modification by consumers. "Most of the refractory magnesite that has been in general use has peculiar and distinctive properties that are not found in the magnesite deposits of the common type. The value of this refractory material depends not only on its resistence to the corrosive action of heat and metallic slags, but also on the permanence of the forms in which it is put into the furnace. This permanence is due to a natural bonding which tends to make the loose crushed material cling together under furnace heat and thus makes brick forms molded from it more durable. Bricks and granular furnace bottoms made of magnesite that lacks this bond break, and the magnesite floats off on the fluid molten metal and is lost in the slag. Thus, though magnesite that contains a small percentage of iron may be somewhat less resistant to extreme heat than a purer form, the slight fusibility given to the material by the iron tends to hold it in place. For this reason, in part, a type of magnesite so far found only in Austria and Hungary has been the principal source of the refractory magnesia used in this country. The purer magnesite from Greece, California, and elsewhere is used in making plaster or cement or material for other relatively minor uses." ' The magnesite developed in the state of Washington is crystalline, resembling limestone and dolomite, and carries a small percentage of iron, being similar to the Austrian magnesite both in appearance and composition. The colors vary through pink, gray, and almost black. Calcined, it is dark brown to blackish. Normally about 5 to 6 pounds of magnesite are used for every ton of steel made by the open-hearth process; but during the World War period the consumption was as low as one-half pound while cheaper, though less-satisfactory substitutes were being employed to make up the deficiency in tonnage of magnesite available. » Gale, H. S, Magnesite: U. S. Genl. Surv., Bull. 666 ('Our Mineral Supplies'), p. 173, 1919. MAGNESITE IN CALIFORNIA. 17 Plastic Uses. The oxide and chloride of certain elements, when mixed, unite and form a very hard cement. This fact was discovered in 1853 by the French chemist. Sorel, who produced a very hard cement, used by dentists, hy mixing zinc oxide and zinc chloride. Later it was found that magnesium oxide and magnesium chloride also produced a very strong cement. ' Oxychloride ' or 'Sorel' cements is the general name given to compounds of this type. The use of magnesite in the manufacture of magnesia oxychloride or Sorel cement is an important one. Products into which the cement enters find many technical applications in structural and other work, and they are apparently growing in popularity. The cement is made by mixing fine-grained, light-calcined magnesite with a solution of magnesium chloride 20°-30^ Baume. The strength of this cement is exceptional and it is very plastic and comparatively cheap. It is extensively used as a binder in the manufacture of emery and other grinding and polishing wheels, where a strong bond is required to prevent bui-sting, and in making artificial stone and tile. The cement sets quickly and does not freeze .so that it may be used at below-zero temperatures. For many structural purposes a filler, which commonly consists of ground marble, sand, sawdust, cork, asbestos or other material com- prising from 10% to 40% of the whole is added together with a pigment to give any desired color, and the composition is then applied in plastic form. The character of the composite material will of cour.se, vary with the filler used. A rough finished .stucco may be made or a smooth tough seamless surface which will take a good wax or oil polish. These compositions will hold firmly to a base of wood, metal, or concrete. As an example of the formulas used in mixing such cements the following are quoted :^ "Mixtures for the underlying or coarser layer. [Parts by weight.] 1. 15 parts magnesia. 10 parts magnesium chloride solution, 20° Baume. 10 parts moist sawdust. (Sets in 36 hours.) -. 10 parts magnesia. 10 parts magnesium chloride solution, 28° Baume. 5 parts sawdust. (Sets in 16 hours.) 3. 20 parts magnesia. 15 parts magnesium chloiide solution, 20° Baume. 4 parts ground cork. (Sets in 24 hours.) 4. 5 parts magnesia. 3 parts magnesium chloride solution, 20° Baum^. 5 parts ashes. (Sets in 24 hours.) Mixtures for overlying or surface layers. , ,^ [I'arts by weight.] 1. 4 jiarts magnesia. ;>3 parts magnesium chloride solution, 19° Baume. 10 parts asbestos powder. 5 parts wood flour. 1 part red oclier. (Sets in 24 hours.) Scherer, Robert— Der Magnesit, sem Vorkommen, seine Gewinnung und technische Verwertung. pp. 216-217. A. Hartleben's Bibliothek. Wien und Leipzig, 190S. 2 — 39802 18 CALIFORNIA STATE MINING BUREAU. 2. 25 parts magnesia. 25 parts magnesium chloride, 21° Baume. 4 J parts wood flour, impregnated with 4 J parts Terpentinharzlosung. 15 parts yellow ocher. (Sets in 30 hours.)" Most of the desirable qualities in a flooring material such as cleanli- ness, quietness, immunity from abrasion, resilience, appearance, water- proof character, elasticity, warmth or thermal insulation, lightness, strength, etc., are apparently met by various magnesia-cement com- pounds. They have proved particularly efficient as a flooring in steel railroad coaches and in various parts of ships. They are extensively used for flooring, stair treads, wainscoting, tiling and for sanitary kitchen, laundry, bathroom and hospital finishing. Many installations have been made in large public buildings, depots, factories, shops and restaurants. The prepared materials, ready either to be mixed with water or with magnesium chloride solution, are on the market under various trade names. Data concerning the percentages of magnesium chloride and ground magnesia as well as that concerning the character and quantity of filler and color matter added are naturally guarded as trade secrets by the manufacturers. Causes of occasional unsatisfactory installations have been ascribed ^ to uncertain climatic changes, lack of uniformity of the mixtures used, lack of care in handling the material, deterioration of the material through exposure either before or after mixing, lack of experience in laying, etc. Some of these causes could probably be eliminated by the standardization of the raw material used and of acceptable filler materials, and by the establishment of standard proportions, with benefit to the industry as a whole. In fact, such improvements are being made, as is later shown herein (see pages 21-33, inc.). For cement purposes the magnesite when burned is left 'caustic,' as distinguished from 'dead burned' magnesite, and contains from 2% to 10% CO,. The conditions of the calcination are important for the same material will undoubtedly vary greatly in its reacting prop- erties with different treatment in the kiln. The magnesite should be comparatively free from lime, which later causes swelling in the cement, but a higher silica content, up to 12%, is not objectionable, provided the association of the silica is not in such a form as to pre- vent proper calcination of the MgCOg. "When properly packed in paper-lined casks, barrels or boxes, the material is fairly permanent, but it deteriorates on exposure. It can probably be kept unopened for a year or more if care is used, but it should be used within a few weeks after being opened even under the most favorable conditions. The manufacture of magnesia oxychloride cement products is undoubtedly a promising field and one in which considerable headway has already" been made in this state. Calif ornian magnesite on account of its exceptional purity, is particularly suitable for plastic uses. • For a detailed account of investigations into the uses and properties of magnesia cements, see : Eng. Soc. Western Pennsylvania, Proc. 1913, vol. 29, pp. 305-338, 418-444. U. S. Geol. Sur., Mineral Resources, 1913, Part II, pp. 450-453. Cal. State Min. Bur., Bulletin 74, pp. 70-72, 1917, contains a summary of the above-listed papers. MAGNESITE IN CALIFORNIA. 19 As a supply af magnesium chloride is essential to the plastic magne- site industry, it is worthy of note, here, that there are five plants at present (May, 1925) in California preparing MgCU from the residual bittern water of salt-works brines. Paper Manufacture. For some years previous to the war by far the greater part of the magnesite mined in California was consumed by the wood-pulp paper mills of the Pacific Coast. In what is known as the sulphite process of making paper from wood pulp, magnesium bisulphite has been found to be one of the best available agents for the digestion of the wood fiber. The bisulphite is made by passing sulphurous fumes through calcined magnesite. Calcium and sodium bisulphite can also be used but cal- cium bisulphite is not as stable as magnesium bisulphite and does not give as good results, while sodium bisulphite, although better than either of the above, is too expensive for general use. There seems to be little likelihood of aiw substitute displacing magnesium bisulphite in this process and the paper mills will no doubt continue to consume a considerable tonnage of magnesite annually. Carbonic Acid Gas. Carbon dioxide (CO,) or carbonic acid gas is one of the products given off during the calcining of magnesite. This gas when com- pressed into liquid form in steel cylinders (about 850 lb. pressure) is easily transported and forms an article of considerable commercial value. It is used by bottlers for carbonating soda-Avater and other beverages; by ice plants and for general refrigerating purposes on ships and elsewhere. Formerly about 1000 tons of crude magnesite was annually calcined by San Francisco firms for the manufacture of carbonic acid gas, but of late years they have obtained the gas mostly from other sources. During the war, one custom calcining plant utilized the derived carbon dioxide and sold the calcined residue to paper mills. According to reports 1 ton of magnesite produces about 500 lb. of gas, when finally compressed into liquid form, and 1200 lb. of calcined magnesite still carrying some 20% of CO,. At most calcining plants, however, the gas is considered simply a waste product and allowed to escape. Miscellaneous Applications. In both crude and calcined form magnesite is being used in an increasing number of ways. Mixed with asbestos it is used as a heat- insulating covering for steam-pipes and boilers. It is said to be used as an absorbent in the manufacture of dynamite; as an adulterant in paints, and as a preventative of boiler scale where sulphurous water is used. It is also used for making damp-proof and fire-retarding mixtures. Concrete buildings are frequently finished with a coat of magnesite paint, and wood and burlap protected by such a coating are said to resist fire so that although they can be burned by the direct application of a fiame, the fire will not spread beyond the area of contact. 20 CALIFORNIA STATE MINING BUREAU. Medicinal Uses. Various refined magnesia salts are used for medicinal purposes and in toilet preparations. Among these are epsom salts (magnesium sul- phate), magnesia alba (basic carbonate) and magnesium chloride. These salts have heretofore been imported in considerable quantities from Germany, but they are also obtained by the chemical treatment of magnesite. Undoubtedly, as a result of the war there will be a large increase in the amount of refined magnesia salts manufactured by American chemical companies, and a correspondingly broader market for the raw materials. Metallic Magnesium. Rather important developments have taken place since 1914, looking toward the increased production of the metal magnesium : First, as a war requisite; and second, to its adaptation to other useful and more desirable purposes. Uses which involve the reduction of magnesium metal from magnesite ores, and a more extensive use of the metal, are attracting the atten- tion of producers. Alloyed with steel, magnesium imparts toughness to the former, and a less weight is required for a given strength. It may be alloyed with aluminum; and it is claimed, as an example, that a 100-lb. aluminum automobile body costing $20 could be displaced by a 40-lb. Al-Mg. alloy giving the same strength and costing the same. It is said that the metal can be produced for 50ff per lb. by a plant at Niagara Falls. An alloy of magnesium with silver is said to make a non-tarnishable 'silver.' F. L. Hess ^ says : "Elemental magnesium is known to comparatively few people and to most of those few chiefly as a silvery powder of low specilic gravity, used in flash lights for photography ; to a few others it is known as a narrow ribbon or as a fine granular substance ; * * * and to a still smaller number it is known in massive form. It seems probable, however, that magnesium will become very much more common and it may become as common as aluminum. "Magnesium as it is now isolated, is a beautiful silvery-white metal. It com- monly becomes coated with a white film of oxide in a few days or weeks ; but several manufacturers have said that they have segregated magnesium having a purity of 99.99 per cent or more, which has remained untarnished or at most has shown no more tarnish than aluminum after an exposure of six to ten months in the open air. It is readily malleable and is ductile when heated. * * * When ignited in air magnesium burns with an intense white light very rich in actinic rays, and this property gives it its value in photographic work. * * * Magnesium is the lightest of the metals now known that remains comparatively unaltered under atmospheric conditions. Its specific gravity (1.74) is only two-thirds that of aluminum (2. 58) and two-ninths that of iron (7.86)." Continuing, he says : "With the beginning of the European war a great demand sprang up for magnesium to be used in the unprecedentedly large quantities of war materials manufactured, but the supply, not only of the metal but of the magnesium chloride used in its manufacture, which had previously come from Germany, was cut off and caused the embarkation of American firms in the business of isolating the metal from minerals of domestic production. * * * xhe total production dur- ing the year 1915 was 87,500 lbs. valued at about $440,000." The metal was generally produced by electrolytic methods from magnesium chloride. Part of this was imported stock, part was obtained from the bittern waters left after the extraction of salt from ocean water or brines, and part was derived from California magnesite. ' U. S. Geol. Surv : Mineral resources of the U. S., 1915, Part I, page 735. MAGNESITE IN CALIFORNIA. 21 In regard to the uses for magnesium, Iless further^ writes: "The largest use during 1915 was in the making of war munitions. It does not enter into explosives nor into arms as an integral part, but small quantities are put in shrapnel shells in order that observers and gunners may know exactly where the shells are bursting. Bv day the burning magnesium gives a dense, pure-white cloud of magnesium oxide, that can be readily and distinctly seen, and at night it gives a dazzling white light. Larger quantities are u.sed in aerial bombs and rockets used for lighting up the country at night. * * * A small quantity of magnesium is also used in fireworks for peaceful displays. A number of tons are used each year for flash lights for photographic purposes. * * * Magnesium has not found much direct use as a metal, but magnalium, an alloy of aluminum, containing 2 rier cent or less of magnesium and small percentages of other metals, is said to be used in automobiles and airplanes. "The value of magnesium as a deoxidizer is utilized by adding it to monel metal or nickel when melted for casting. It has been used in steel for the same purpose but has so far not displaced aluminum to any large extent, though it is used by some steel makers. Small quantities are used in chemistry. « * * "Among the uses of magnesium to which manufacturers look forward are its employment to replace aluminum as a deoxidizer in steel, and also to replace aluminum, in part, in automobiles and airplanes." Among other firms, The American Magnesium Corporation, Niagara Falls, N. Y., now offers, according to current trade journal advertise- ments, magnesium bars — 99% pure, magnesium-aluminum alloys, magnesium-silicon alloys, magnesium-copper alloys, and magnesium powder^ In view of the great variety, the recognized utility, and the sub- stantial value of the products obtained from the mineral magnesite it seems certain that the deposits in California must continue to be the center of much interest, not only to those directly interested in magne- site mining, but to a large portion of that class engaged in manufac- turing various finished products from the raw material, who from force of circumstances or by preference, wish to obtain their supplies from domestic sources. TESTING AND SPECIFICATIONS FOR MAGNESIUM OXYCHLORIDE CEMENTS. Reliable and conclusive testing of plastic calcined magnesite has long been a serious problem to users of this material. Attempts to regulate quality by chemical specifications have not been successful. Unfortu- nately, it has been found that much poor as well as good calcined mag- nesite will meet many of such chemical specifications. "The industry in general is coming to believe that a specification for this product should be written on the basis of physical tests only, with entire elimination of chemical analysis. The physical tests ordinarily recommended are those for fineness of calcined magnesite, and for strength, constancy of volume, setting time, and resistance to water of the finished cement. Tests of this nature unquestionably furnish valuable information as to the quality in calcined magnesite. It is inter- esting to compare such test results with the results of chemical analysis and particularly to search for special analytical determinations which might throw light on the question of quality before totally abandoning the use of chemical tests." - According to Seaton.^ "The chemist has long known that the magnesium oxy-chlorides were decom- posed by water, with the formation of magnesium chloride in solution and the precipitation of magnesium hydrate. By many this fact has been considered to mean that oxy-chloride cements could never withstand the action of water without serious loss in cementing properties and consequent deterioration in structural value of any material in which oxy-chlorides were used. Such reasoning is fallacious. Certain forms of magnesium hydrate closely resemble the natural mineral bruclte, »Op. cit., p. 740. -Seaton, Hill and Stewart: Chem. & Met. Eng., Vol. 25, Aug. 17, 1921. ^ Seaton, M. Y., Magnesium oxychloride cements: Chemical Age, Vol. 31, pp. 17-2r Jan. 1923. 22 CALIFORNIA STATE MINING BUREAU. which is magnesium hydroxide, in properties, having high strength and excellent binding power. Fortunately, it is to these forms of hydrate that oxy-chlorides revert when such oxy-chlorides are of proper constitution and are weathered or wet in normal fashion. The recollection that the calcium hydrate in lime mortars is slowly transformed to calcium carbonate on aging should be sufficient to lay at rest the fear that a change in the composition of a cementing material need neces- sarily result in structural unsoundness. "The solid solution which always constitutes a major part of magnesium oxy- chloride cement contains a considerable amount of water. Its water content varies according to its environment, being lower as temperature rises and humidity of the air drops, and higher as the reverse changes take place. As water content is reduced, slight shrinkage of the oxy-chloride results while slight expansion follows increase in water content. This is exceedingly fortunate, for it tends to counter- act the normal volume changes which occur through temperature change. That is, the usual expansion with rise in temperature is, with the oxy-chlorides, coun- teracted, at least in part, by the shrinkage caused tlirough loss in water of the basic binding material. It is particularly for this reason that the oxy-chlorides have the name of being remarkably free from expansion or contraction movements. ******* "Specifications. "Consumers of plastic calcined magnesite throughout the early development of the industry experienced grave difficulty in purchasing a product of satisfactory cement- making properties. Plastic calcined magnesite was sold wholly on analytical specifica- tions, the content of magnesium oxide, of ignition loss and of lime ordinarily being kept within moderately close limits. It developed that magnesium oxides of identical chemical analysis did not necessarily have comparable cement-making value. At the joint instigation of tlie world's largest oxy-chloride producer and of the largest magnesium chloride producer in the United States investigations were undertaken which ended in showing the causes for the discrepancies pre- viously noted, and for the first time establisliing the industry on a substantial basis. "The gypsum and the Portland cement industries have definitely established that the physical character and cement-making value of their products cannot be specified in terms of chemical analysis. The lime industry has recently found the same facts to hold true for its particular field. A parallel case exists in plastic calcined magnesite. Laboratory investigators have long known that the reactivity of magnesium oxide was largely a function of the time-temperature history of its calcination. At one extreme stands the active oxide first formed when carbon dioxide is just barely removed from the natural carbonate, while at the other extreme artificial periclase is found. This is still magnesium oxide, but shows no ability to react with magnesium chloride solution or to become hydrated In contact with water. Neither of these products is satisfactory when used in the preparation oxy-chloride or Sorel cements. The material desired lies somewhere between these two extremes. Unfortunately, there are as yet no methods which will rapidly identify the particular oxide which the oxy-chloride industry needs. Recourse must be had to the preparation of oxy-chloride cements and the exam- ination of their physical properties. In other words, physical tests have practi- cally wliolly replaced the chemical tests once relied on, and it is through such physical tests that all production of magnesite should be guided. "Production. "Formerly all plastic calcined magnesite was prepared in stack ot upright kilns of the type of the familiar vertical lime-kiln, and such kilns still persist in some California operations, although their product can never approach in qu.ality the material obtained from other types of furnaces. If a magnesium oxide of high quality is to be prepared, time and temperature of calcination must be held within narrow limits. This is obviously impossible in the burning of lump ore in a stack kiln, where to insure heat penetration and decarbonization to the center of the lump so much heat must be supplied that the outer material is seriously over-burned. For production of high-quality material the ore must be sized within Quite narrow limits, and a kiln or furnace adapted for burning such fine ore employed. Up to this time, because of the temperature involved, the rotary kiln only has been in active use. The Wedge or Herreshoff furnace may, perhaps, find a field in the treatment of the higher-iron ores, which calcine at a low temperature, but it is doubtful whether they will withstand the temperatures involved in the treatment of the purer ores, which must be heated to approximately 1,100° C. "In mining operations care must be taken to hold the analysis of the ore delivered to a calcining plant within quite narrow limits. This is the principal place in the, magnesite calcining industry where chemical analysis is of vital importance. As calcium carbonate is fairly completely decomposed at the calcining temperatures employed and as the resulting calcium oxide is exceedingly injurious to the oxy- chloride reaction, 1 lime content must be held at a low figure. Then, too, small amounts of certain substances, notably iron, and to a lesser extent alumina and silica, influence catalytically the reactions which occur during magnesite calcining. If they are present in quantity, calcining temperatures must be lowered materially to avoid over-burning. These impurities are not injurious in the sense that lime is, but ore containing them must be kept separate from ore containing no such material and treated in individual fashion in order to yield a satisfactory product. "No particular comment is called for on the general operations of mining or of crushing the ore before calcination. In practice it is found that half-inch sizing is essential if the appearance of either over-burned or under-burned materal in the finished product is to be avoided. Kiln practice, however, is essentially differ- ^ See in this connection, Seaton, Hill and Stewart, Chem. & Met. Eng., Vol. 25, page 270. MAGNESITE IN CALIFORNIA. 23 ent from that common in either the cement or the lime industries, although it is conceivable that the lime industry will some day, employ the methods used in the preparation of calcined magnesite. In the operation of a rotary kiln for magnesite production not only must the maximum temperature in the kiln be carefully regu- lated, but a temperature closely approaching the maximum must be maintained over a zone of considerable length. In normal practice the carbon dioxide is expelled from the magnesite at a temperature much below that necessary for the develop- ment of the particular type of magnesium oxide which is desired. Gas is fairly well liberated, in other words, before the ore enters the zone in the kiln in which definite temperature is maintained. It is the length of this zone, its temperature and the rate of passage of magnesite down the kiln which determine the character of the calcined product. ♦ «****• "The calcined magnesite must be ground to a product somewhat finer than ordinary Portland cement. For this grinding the use of ball or tube mills is not permissible, because of the packing of the material on the sides of .such a mill. The ring roll-mill using air separation or the burrstone mill give excellent products. For this particular grinding problem the old-fashioned burr mill, which has fallen into disrepute in many industries, is particularly adapted and gives a material diflficult to equal by any other type of mill. "The finished plastic calcined magnesite is a fine powder, about 85 per cent of which passes a 200-mesh screen. It varies in color from white through creams to dark browns or even chocolates. The darker-colored product may have intrin- sically the same cement making properties as the lighter materials, giving only a cement of darker color, and consequently limited to use to those cases where color in the finished product is no object. The cream-colored magnesite may give even a whiter cement than the pure white rhagnesite. "Raw Materials — Magnesiuvi Chloride. "Magnesium chloride is also an essential raw material for the industry. The potash deposits in the Stassfurt region in Germany contain, of course, enormous quantities of magnesium chloride, which in more or less impure form is a waste product from potash plants. German magnesium chloride was for many years the standard of the industry in the United States, but particularly since the war domestic production has taken the place of first importance. "Addition of Aaareaates. "The remaining raw materials of Interest to the industry may be classed under the general head of aggregates, and require very close attention by operators producing oxy-chloride cements. For a number of reasons the practice of assembl- ing mixes at the point where they are to be applied — that is, adding sand and other aggregates to the magnesium oxide in the field — is not permissible. In the first place, only dry aggregates can be used, as the oxy-chloride cements are very sensitive to variation in the strength of magnesium chloride employed in their preparation. If wet aggregates are used it is impossible to make proper adjust- ment for the varying amount of water thus introduced. Furthernaore, a special knowledge is required for the choice of satisfactory aggregates. "Not only are more materials needed than are employed in concrete or gypsum plaster practice, where sand or sand and stone only are required, but the requirements for a satisfactory sand are quite different from those which hold in the prepara- tion of high quality concrete. If sand only were needed in oxy-chloride cements, education or the insistence on special screening methods might solve the difficulty. All commercial products, however, contain a fine aggregate, such as silex or marbledust, and almost invariably a fibrous material such as asbestos. These materials, of standardized quality, are not available locally at the points where such cements are used. An even more vital factor in eliminating the possibility of field-prepared mixes is the fact that the principles of oxy-chloride mix forma- tion are perhaps more complicated than those which hold for concretes. Mix balance is not improved by adding more magnesite as a factor of safety to take care of inferior aggregates, as can be done with Portland cement in concrete work. Instead, the quality of an oxy-chloride mix is deteriorated if either too much or too little magnesium oxide is employed, and for best results the quantity of oxide used must be carefully regulated to the characteristics of the other materials used in the mix. For this reason factory prepared mixes are the standards in the oxy-chloride industry, and despite the disadvantages of such mixes in somewhat higher cost for transportation there is little likelihood of the use of field prepared mixes gaining in favor. "The most fundamental principle involved in the formation of suitable oxy- chloride mixes may be described as the 'thin glue joint' principle. It is common knowledge -that in gluing two pieces of wood best mechanical properties, are obtained when the glue film interposed between the two wood surfaces is of minimum thickness. Exactly the same principle holds for oxy-chlotide mixes. TJie magnesium oxide-magnesium "chloride mix which eventually gives an oxy-chloride of some indefinite composition should be considered as a mineral glue which will function to best advantage only when it is present as thin films between closely packed particles of aggregate. Because the reaction between magnesium oxide and chloride is almost totally complete, without the surface reaction effect which exists between Portland cement particles and water, it is necessary to supply fine aggregate to partially fill the voids between the coarser sand particles. If this is not done, so large a volume of oxy-chloride cement appears between sand grains that the thin 24 CALIFORNIA STATE MINING BUREAU. glue jfjint principle is violated and weakness results. It is obvious that in follow- ing out this principle a mix of high density is unavoidably obtained. '•Oxv-chloride cements are finally used in by far the majority of cases by work- men of only ordinary skill, who in most instances handle the plastic cement with trowels or similar tools. It is obvious that such a worker will obtain best mechanical results if the mix he works with is easy to handle and can be applied with only normal effort. For this reason attention is given by oxy-chloride manufacturers to the production of high plasticity in their finished materials. This is usually done through the addition of asbestos or a related fibrous material. Fortunately, as will be later shown, such an addition is permissible here, and the change in ratio of liquid to solid resulting is not detrimental, as it is in Portland cement Dr3.ctic6- "Of vital importance too in the preparation of oxy-chloride cements is the question of the strength of the magnesium chloride solution employed. General experience has indicated that a solution of a gravity of 22° Baume gives best results, and that if this strength is greatly departed from trouble will result." The same writer further states ^ "The fundamental point back of the adoption of physical tests of quality criteria for calcined magnesite lies in the observation that magnesium oxide may exist in different forms, which, although they show the same chemical analysis, behave entirely differently in the oxy-chloride reaction, and give cements of widely varying character. They range from the exceedingly active oxide, showing rapid reaction with magnesium chloride but giving a cement of undesirable properties, which is first formed on heating natural magnesite, to the wholly inactive periclase which results from burning at high temperatvires. While 'dead burn' magnesia is desired by the refractory user, it is useless to an oxy-chloride producer. Although much thought has l^een given to the question of the constitution of these different oxides, and although they have been examined by every modern method known to the chemist and the physicist, we are still without any too definite knowledge of their constitution, and without quantitative method for their determination. "While there is now quite universal recognition of the value of physical tests in the examination of magnesites, there is still some difference of opinion as to the part which chemical analysis should play in the industry. From the purchaser's standpoint, it may be positively concluded that analytical determinations will give no useful index of the value of plastic magnesia. The most common argument of the analyst is that a magnesite containing 9090 of magnesium oxide should be considerably better than one containing 70% magnesium oxide. If the chemist's determination could indicate the reactive content of magnesium oxide, this would be the case, but it is entirely possible that a 70% MgO material may contain more active magnesium oxide per unit weight than the material showing an analysis of 90%. iii iii * * * ^ ^ "If the worth of a calcined magnesite is to be judged from the physical properties of an oxv-chloride mix in which the magnesite is used, it is essential that the char- acter and gradation of the other ingredients used in the testing mix must from a practical standpoint, be kept constant at all times. A mix subscribed to some time ago bv a committee of the producers of domestic magnesite, (including repre- sentatives from the U. S. Bureau of Standards and U. S. Bureau of Mines) has. to the best of our knowledge, not been materially bettered by any subsequent work. It follows, in make-up, the principles which have proven themselves sound in extensive field practice. It is composed of ingredients easy to obtain in any locality, and gives a mix of normal, well balanced properties. It contains five parts of Standard Ottawa Sand, screened between 20 and 30 meshes ; two parts of Silex or Ground Silica, which practically completely passes a 100-mesh screen and shows about 75% passing a 200-mesh screen; and one part of the calcined magnesite under test. With this mix a solution of magnesium chloride of a gravity of 22° Baume is used, such solution being prepared from a magnesium chloride showing not over 2% of magnesium sulphate, 2% of calcium chloride, or 2% of salt, on a fused magnesium chloride basis. This solution is added to the well mixed dry ingredients until a mortar is obtained of such consistency that it will just support a flat-ended metal cylinder one inch in diameter and weighing 250 grams. Specimens made of such mixes are then subjected to various tests to establish various values of the magnesium oxide as a cementing medium. The results obtained from examination of magnesites by use of such a mix have been invaluable both from a consumer's and producer's standpoint. ******* "Tests of the setting time of a calcined magnesite are almost invariably required. It is necessary to employ the standard testing mix for this determination, just as for the determination of physical strength, for the setting time of a neat mixture of magnesite and magnesium chloride bears little relation to the beha.vior which this same magnesite exhibits in the complex mixes in which it is ordinarily employed. On mortars of the testing mix, setting time may be determined by use of standard Gilmore needles. The Vicat needle is not applicable because of the coarseness of the mix. Care must be taken in examining the impressions made by the Gilmore needles, as the marks are by no means as sharp and distinct as they are on the fine grained pats of neat Portland cement usually tested. "There is probably no property of plastic calcined magnesite which is more mis- understood or is the' subject of more disputes than is that of its time of set. It 1 Seaton, M. Y., Magnesite testing practice : Pamphlet issued by the Sierra Magne- ,site Company, 1923. MAGNESITE IN CALIFORNIA. 25 is not generally recognized that temperature of tlie atmosphere at the point where an oxv-chloride mix is applied exerts an enormous effect on setting time. The same product which might meet a customer's requirements exactly under moderate atmospheric conditions, would perhaps prove far too fast setting during extreme summer weatlier, or far too slow setting in cool damp weather. The setting time of an oxy-chloride mix is roughly reduced to half its original value when temperature rises fiom the normal 70° at which most tests are specified, to 100°, while the time for .set is doubled if the temperature drops from 70° to 50°. Humidity also exerts a pronounced effect on setting time, high humidity increasing time of set, and low humidity reducing it. Perhaps more important still is the effect which change in the character of tlie commercial mix in which the magnesite is used exerts. Thus, a mix higli in asbestos and wood flour may require from one and a half to four times as long for setting as does the standard testing mix, while on the other hand a high magnesite percentage flooring, particularly of the mineral type, may set faster than the standard testing mix. Magnesite consumers should realize tliat. constant setting time can never be secured unless temperature is held constant and if no material change i-s made in the character of mix employed. A surprising difference in time of set is noted by so common and unappreciated a change in mix characteristic as a variation in the grading of silicas or other aggre- gate. Then too, variations in the time of reaction or set is occasioned by the time that may lapse between the time the magnesite is calcined and the time it is used. Generally, freshly calcined magnesite reacts more rapidly than magnesite that has been stored for a considerable period of time. ******* "It should be realized that oxy-chloride products in well over 95% of the cases in which they are used are employed in the form of thin layers applied either to floor or to wall surfaces. Up to the present time, they have not yet been used in mass work, sucli as Portland cement concrete is. All successful oxy-chloride prac- tice in the field involves tlie free exposure of thin layers of the product to the cir- culating and drying influence of the atmosphere. Probably the main reason that oxy-chloride strength tests in most instances have failed to give a true index of the character of the product is because an attempt has been made to apply to oxy-chloride mixes the methods ordinarily employed in the testing of Portland cement. These methods are designed for use on a material of radically different charac- teristics from the oxy-chlorides. All of the major uses of concrete involve its application in masses of considerable dimensions, and it is aged either under water or in moist atmosphere. Concrete design is drawn so that concrete must resist compressive stresses only. In fact, in the ordinary calculations, the tensile strength of concrete is not allowed for. although tension tests of concrete mortars are still made, test pieces being in the form of the well known briquettes, which are aged under water for seven or twenty-eight days. * * * Neither tensile briquettes nor compression cubes or cylinders can be aged under exposure conditions even approximating those existing in oxy-chloride field work, particularly during their early age, when surface evaporation is of paramount importance, "It is not generally recognized that conditions of temperature and humidity of the atmosphere in which oxy-chloride test pieces are made and stored exert an enormous influence on the results obtained. In cement testing practice, an artificial atmosphere saturated with water is maintained, or test pieces are actually immersed in water, for the reason that Portland cement is essentially a hydraulic material. Oxy-chloride cement is not a hydraulic cement and it will not set under these circumstances. Consequently, oxy-chloride cements, in order to set, must he exposed to the air, which may vary greatly in properties. Accordingly, an opera- tor may make tests of an identical mix on two different days on which temperature differs perhaps 20° and humidity 30 or 40 points, and be surprised because duplicate values are not obtained. As a matter of fact, he should be more surprised if his values did approach each other, for they actually should differ considerably under such circumstances. "Sound testing practice for determination of the strength of oxy-chloride cements involves first, the use of test pieces which can be aged under conditions approxi- mating those that exist in the field application of oxy-chloride products ; and second, the regulation of temperature and humidit;^ conditions in the atmosphere of the testing laboratories within quite narrow limits. The first of those requirements can be met by preparing test pieces, in the form of flat bars, not over one-half inch in thickness, which are allowed free exposure to the air and which can be tested for strength by breaking in a cross-bending machine of any simple design. Com- parison of tests made in this fashion with briquette tests on the same mixes made at the same time shows that there is little relation between the values obtained. Depending on the type of mix and the character of magnesite employed, the ratio between a cross-bending test of thin flat bars and the ordinary briquette test varies between 1.5 and 3.2. Such a variation is the best po.ssible argument for the adoption of one only of these tests as a standard. Inasmuch as it is obvious that the flat bar is aged far more nearly under the same conditions which exist in the field than is the briquette, the bar test is preferable for all work in checking oxy-chloride quality. In order that the respective values of different magnesites may be deter- mined, the same kinds of series of tests, with the same kind of apparatus and con- ducted under nearly equal atmospheric conditions should be adopted. Otherwise the determinations of one laboratory will not even approximate the findings of another. ******* "The question of the minimum strength permissible in a given magnesite when made into the standard mix is a somewhat difllcult one. To obtain thoroughly desirable properties in all respects the magnesite producer almost invariably finds it necessary to make moderate concessions from the strength that it is possible to produce. The fact is that in most cases far too much importance is attached to high early strengths. A product showing a modulus of rupture In crosg-bending of 26 CALIFORNIA STATE MINING BUREAU. 400 pounds at one day, 900 pounds at seven days, and 1250 pounds at thirty days, undoubtedly has ample strength to meet all practical requirements of the industry. One of the most serious mistakes which appears in past and current oxy-chloride practice is the idea that high strength is a criterion of quality in a calcined magne- site. High strength is obviously an advantage, but it is frequently not recognized that a material may have enormous strength and yet be so deficient in the other properties whicli are required for satisfactory field practice as to be next to valueless. Too many operators draw tlieir conclusions as to magnesite quality from strengtli tests alone, and thus seriously mislead themselves on the quality question. Of two products, one showing 1000 pounds cross-bending strengtli at fourteen days and increasing this strength 50% after prolonged contact with water, and another showing a strength of 2000 pounds but losing two-thirds of this strength after the same water contact, there can be little doubt as to which is superior. "This last example brings us logically to the ciuestion of water resistance tests of oxy-chloride mixes as a factor in determination of magnesite quality Essentially all oxy-chloride products used for stucco or flooring work are subject to periodic contact with water. Good water resistance is also desirable in magnesite used for interior plaster. It has only been realized comparatively recently that the marked difference in behavior of oxy-chloride floorings, stuccos or other products with reference to their ability to witlistand water and dampness is a function of the quality of the calcined magnesite employed more than it is of any other single factor. The literature yields many instances of wide variation in the water resistance of oxy-chloride products, some authors stating that such materials disintegrate rapidly in contact even with damp air, while others maintain that they withstand water perfectly. These discrepancies are explained when it is realized that different investigators have worked with different calcined magnesites, and that these products can readily introduce as great differences in behavior as those recorded. It is felt, accordingly, that a test for water resistance is vitally essential in the determination of the value of any calcined magnesite. "Some misconception exists as to the permissible methods of making water resistance tests. Tests are frequently reported in which an oxy-chloride test piece of some description is immersed in a small volume of water and allowed to remain for a considerable period, tlien removed and tested. Such conditions are very far removed from the circumstances to which any oxy-chloride product is normally subjected in the field. Steam and boiling experiments are also sometimes vaguely applied. Practical value comparisons can not be obtained from such 'stunts.' "Care is also taken in the installation of oxy-chloride materials to insure ample drainage of wall or floor, and it is pointed out by all operators that arrangements for such drainage are essential if successful results are to be obtained. Experiment shows that when test pieces are immersed in still or stagnant water, this water extracts a certain portion of the magnesium chloride from the oxy-chloride cement, thus itself becoming a solution of magnesium chloride. The test, therefore, soon becomes that of immersion of a oxy-chloride specimen in a magnesium chloride solu- tion rather than immersion in water. Magnesium chloride solutions exert a disastrous disintegrating effect on oxy-chloride cements, and it is easy to see, accordingly, how an improperly applied water resistence test can hardly fail to give misleading information. Proper procedure involves either the immersion of test pieces in circulating clear water, or more correctly, their subjection to fine water spray. This latter procedure more closely parallels service conditions, particularly for the stucco industry, which is specially interested in water resistance tests. A procedure which has been found particularly valuable, also recommended by the magnesite producers committee before referred to, is that of aging flat bars for a period of fourten days, spraying two-thirds of the specimens for three twenty-four- hour periods with intervening twenty-four-hour drying periods, breaking half of the sprayed specimens wet, redrying the other half two days and then breaking, and at the same time breaking the original third of the specimens which have not been treated with water. Results can be recorded as dry strengths, wet strengths and recovered strengths. E.xperience has shown that for a material of high quality tested under these conditions, wet strength should be at least 50% of dry strength, and recovered strength 90% or better of dry strength. In fact, the Sierra Magnesite Company has found it possible to consistently produce a material showing a recovered strength under these conditions of 100% to 150% of dry strength. ******* "Tests for warping, buckling, expanding and contracting properties of a calcined magnesite by use of the standard testing mix also furnish valuable information as to its properties, although there are no tests which are more difficult to inter- pret than these. The test itself is comparatively simple to make. Flat bars of the oxy-chloride mix about one-half inch thick, two inches wide and some twelve inches long, prepared on waxed paper so that their movement is totally unrestrained, can have inserted into their upper surface while they are still soft two metal clips carrying punch marks, which are set approximately ten inches apart by aid of the reference bar accompanying the usual Berry strain gauge. Measurement of the position of these punch marks is then taken at the period of initial set, by the Berry gauge, and the movement of the bar as reflected by the changed position of these reference points measured from tima to time with the instrument in ques- tion, readings being made to one-ten-thousandth of an inch. "Another dangerous property of certain magnesite, observable through expansion measurements, is tlie property which some such materials possess of expanding radically when exposed to moist air. Instances of failure of composition floors by buckling have in some instances been traced to this property in the calcined magnesite used. Fortunately, however, it is found that materials of high water resistance do not exhibit this behavior, and accordingly if a material is satisfactory in the water resistance test the added time and trouble of making an expansion test in moist air is not always considered necessary. MAGNESITE IN CALIFORNIA. 27 "Many other tests of lesser importance than the ones previously enumerated are made on occasion on samples of calcined maenesite, using the standard oxy-chloride testing mix previously described. Of these miscellaneous tests, the one most com- monly made is probably the test for water absorption of a specimen, frequently carried out by immersing the sample in water for an extended period, and com- paring its wet weight with the dry weight of the same piece. A test of this kind is subject to grave error, because of the fact that ihe oxy-chloride themselves take on water of constitution when treated in this fashion, and gain of weight is always found, even though the theoretical idea of complete freedom from pores or voids could be reached. "The wide influence of mix character on oxy-chloride tests has been previously mentioned, particularly in the discussion of setting time. Mix constitution affects all the properties ordinarilv determined just as radically as it does the rate of set. The per cent of asbestos or fibrous material, the fineness and general char- acter of the fine aggregate employed, fineness to which magnesite is ground, the shape and size of the sand particles, all influence strength, water resistance, expansion and contraction, and in fact nearly all the physical properties of a mix. Although the character of a calcined magnesite is probably the most vital factor in determining the character of any oxy-chloride mix, it should be thoroughly understood that even the use of a calcined magnesite of ideal properties will not insure the obtaining of good field results from a mix unless the ingredients employed are of proper character and unless they are used in such proportions as to allow of the satisfactory development of the necessary strength, ability to withstand water, and other factors. • * * "Illusion Xo. 1 — The High Strength Fallacy. "Judging magnesite quality by breaking strength tests, an almost universal misconception, is not only an erroneous practice, but it is also dangerously mislead- ing. Any reasonably good grade of crude magnesite ore, can be calcined in such a manner that cements attaining amazingly high strength may be made with it. However, careful study and field observations have conclusively proven that a great many magnesites which have exhibited abnormally high breaking strengths, have failed miserably when subjected to routine service conditions for which such products were intended. "Strength limits assuring reasonable factors of safety are, of course, indispensable. But it is of far greater importance that certain other elements in magnesite, depending upon their effect on the worth of the finished product, be developed or controlled. "Illusion No. 2 — Purchasing by Sample. "Up to the present time, few if any manufacturers of oxy-chloride materials have specialized on magnesite testing to the extent that their findings can be considered as accurate as the determinations arrived at by technical bureaus which handle this particular line of work continuously and exclusively. "Before deciding to purchase magnesite, users in most cases indicate a desire to test a sample of the magnesite offered. Such tests in many instances intro- duce an element of false security, for the reason that an elementary study of a sample is no indication of the character or uniformity of the magnesite the seller may later be able to deliver. "For the average manufacturer who does not maintain a fully organized labora- tory and technical staff, we have to suggest that it will be more advantageous to apply such practical considerations as are below noted in an effort to form an opinion of magnesite quality, rather than to depend upon rudimentary observations of a sample lot of material. "1. Investigate the producer's reputation, his organization, his record for fair dealing and his financial responsibility. "2. Learn through reliable sources the quality of the crude ore contained in his deposits. Ascertain the location and extent of his ore reserves. Also their accessi- bility to transportation in order that you may know that uninterrupted deliveries and efficient service will be assured throughout every month in the year. "3. Satisfy yourself concerning the experience and responsibility of those in charge of plant and laboratory facilities, for upon them scientific and accurate control and production processes is dependent. "Hakeem, the wise man of Bagdad, once said 'The priceless ingredient of every product is the honor and integrity of him who makes it ; consider his name before you buy.' "These things are of more importance in deciding upon entering into a contract for the purchase of magnesite than examination of samples that may be submitted. If you learn through personal investigation that a producer of calcined magnesite employs scientific, intelligent production methods, it creates confidence in that producer and his product." The effect of lime in calcined magnesite has always been considered deleterious ; but apparently the form in which it occurs is important. "Inert and Active Lime. "From the start some distinctioji as to the form In which the lime occurs must be made. In many oxy-chloride cement mixes marble dust or limestone powder is deliberately used as an aggregate without exerting any harmful Influence on the properties of the cement. Such forms of calcium carbonate act merely as inert material, their effect on the character of the cement being roughly equivalent to 28 CALIFORNIA STATE MINING BUREAU. that of a fine sand or ground silica of equal fineness. The report of the presence of a definite amount of lime in a calcined magnesite is accordingly meaningless unless the form in which it occurs be also specified. It is well established that addition of calcium oxide or hydroxide to an oxychloride mix markedly diminishes its strength. Lime in this form or, more exactly, any form of lime which exerts an injurious effect on the quality of an oxychloride can well be designated as 'active lime,' and it would be expected that a determination of the content of lime of tliis character would be of considerable value. "The reduction in strength caused by addition of lime to oxychloride cements has been mentioned by several writers * * *. If the magnesite was burned at a temperature exceeding 1000 deg. C, the lime was slowly and incompletely dis- solved, but magnesites burned at lower temperatures gave good results. 4e ;f; 3)c -K- ,{: 4: ,ie "Summary. "Methods for determination of 'free' and of 'active' lime in plastic calcined magnesites have been indicated, and the distinction between total lime and active lime in such material brought out. "A relation between active lime content of calcined magnesites and physical properties of the oxychloride cements produced from, them has been brought out. "The relationship between active lime content and physical properties of oxy- chloride is apparent only when average results from many samples are considered. Other factors may completely obscure the relation in a test on a single sample. "Active lime content is accordingly not a definite indication of poor quality in a magnesite, although a magnesite containing active lime in large amount should be regarded with suspicion. "Physical tests of oxychloride cements must still be regarded as the only safe criterion of the quality of magnesite used in the oxychloride industries." ' The specifications and tests which follow, herewith, Avere adopted as 'standard' by the National Association of Oxychloride Mannfactnrers at their 1924 meeting, and Avere furnished the author of this bulletin through the courtesy of Mr. Max Y. Seaton, technical director of the Sierra Magnesite Company, who states - "One or two constants are still lacking from the specifications but the testing methods are well developed and the current publication represents, we believe, a decided advance in oxychloride cement testing practice. "It should be mentioned in these as in any other specifications in their early state, values are low rather than high. For example, our own plant here in Porter- ville is consistently shipping material between 20 and 40% higher in strength than the limits set and with perhaps only one-third of the expansion changes indicated. Furthermore, we are using constantly several other tests, notably a water resistance test which we ourselves believe is of very great value in judging magnesite quality which do not appear in the specifications as written. "Various members of the Association are actively working on improved methods for determination of consistency of oxy-chloride mortars, for color of oxy-chloride cements rather than of the magnesite itself and on improvements in the linear change measurements which are felt to be the weakest spot in the specification, but as yet there is nothing definite enough to warrant change in the specifications as they are now written." STANDARD SPECIFICATIONS AND TESTS FOR PLASTIC MAGNESIA. Adopted by the National Association of Oxychloride Manufacturers (1924). DEFINITION. 1. Plastic Magnesia is a magnesium oxide which, when mixed with magnesium chloride solution of proper strength and with suitable fillers, sets to a hard cement. I. Chemical Properties. CHEMICAL LIMITS. 2. Although a chemical analysis may furnish information to manufacturers of certain products in which plastic magnesia is used, no definite relations have been traced between the chemical composition of plastic magnesia and the physical properties of the resulting oxychloride cements. A chemical analysis may or may not be made at the option of the purchaser but, provided the material meets the specifications as to physical properties herein contained, such chemical analysis shall not be considered grounds for the rejection of the material. II. Physical Properties. COLOR. 3. The color of plastic magnesia shall be equal to or lighter than the color standard for the grade of magnesia specified by the purchaser. > Seaton, M. Y., Hill, C. R., and Stewart, L. C, Action of lime in magnesium oxychloride cements: Chem. & Met. Eng., Vol. 25, Aug. 17, 1921. 2 Personal communication to author, April 13, 1925. MAGNESITE IN CAIJFORNIA. 29 FINENESS. 4 The residue on a standard No. 100 sieve shall not exceed three per cent by weight. The residue on a standard No. 200 sieve shall not exceed twenty-five per cent by weight. TIME OF SETTING. 5 The plastic magnesia when mixed in standard mix to normal consistency (See Sections 9 and 10) and when stored under standard conditions (See Section 11) shall not develop initial set in less than one hour. Final set shall be attained within eight hours. STRENGTH. 6 The average modulus of rupture in pounds per square inch of not less than three standard test bars (or of three tests on a twenty inch bar) (See Section 44) shall be equal to or higher than the following: Age of Test Storage Conditions Modulus of Rupture Davs Lbs./Sq. In. 1 Standard 500 7 Standard 900 7. The average modulus of rupture at seven days shall be higher than the value at one day. . , ^ , ^i. ^v. 8 The average tensile strength in pounds per sq. in. of not less than three standard briquettes shall be equal to or higher than the following : Age of Tests, Days Storage Conditions Tensile Strength 1 Standard 200 7 Standard 350 9. The average tensile strength at seven days shall be higher than the value at one day. LINEAR CHANGE. 10. Plastic magnesia when mixed in standard mix to normal consistency shall show not more than the following linear change : Storage Initial Final Linear Conditions Measurement Measurement Change Standard Final Set 24 Hrs. after — .10% Final Set Standard Final Set 24 Hrs. after +.15% Final Set III. Packages, Marking and Storage. PACKAGES AND MARKING. 11. Plastic magnesia shall be delivered in suitable bags or barrels with the brand or name of the manufacturer plainly marked thereon, unless shipped in bulk. STORAGE. 12. Plastic magnesia shall be stored in such manner as to permit easy access for proper inspection and identification of each shipment and in a suitable weather- tight building which will protect it from dampness. IV. InsDection. INSPECTION. 13. Every facility shall be provided the purchaser for careful sampling and inspection either at the mill or at such other point as may be specified by the terms of purchase agreement or contract. V. Rejection. REJECTION. 14. The calcined magnesia may be rejected if it fails to meet any of the require- ments of these specifications. TESTS. VI. Sampling. SAMPLING. 15. A composite sample shall be takt-n from each car or fraction thereof. Such composite sample shall be prepared by mixing individual samples taken from at least each two thousand pound lot of the shipment. A composite sample shall weigh eight to ten pounds. 16. Samjjles shall be shipped or stored in air-tight containers. If the sample contains lumps or foreign material, it shall be passed through a sieve having twenty mesh per linear inch to remove these. 17. Samples from individual packages in the shipment may be separately tested at the purchaser's option. Failure of any such individual sample to meet these specifications may constitute cause for rejection of the entire shipment. 30 CALIFORNIA STATE MINING BUREAU. VII. Determination of Color. COLOR STANDARDS. 18. .Four standard color samples shall bo used for comparison purposes. A. White. B. Light C. Medium dark. D. Dark. 19. Standard color samples are in the hands of the secretary of the Committee on Magnesite Specifications and will be furnished upon request. METHOD. 20. For comparison of color a small amount of the standard shall be placed In a heap beside a similar heap of the material under tests on a flat surface. The two heaps shall be leveled off and brought to a .sharp junction by use of a spatula. If the material is equal to or lighter than the color sample with which it is compared, it shall be considered to fall in the grade of that sample. If darker in color, it shall be compared with the color sample of the next lower grade. Note — Nothing in the specifications for color should be taken to mean that the color grade of the plastic magnesia is an exact measure of the color of the cement made therefrom, although there is some relation between these colors. The color of the finished cement can only be determined after making up a trial lot from the particular materials which are to be used. VIII. Determination of Fineness. APPARATUS. 21. The standard No. 100 and No. 200 sieves used shall conform to the specifica- tions for standard sieves of the the U. S. Bureau of Standards. METHOD. 2 2. The residue on No. 200 mesh sieve shall first be determined. A test shall be made with 50 grams of plastic magnesia. The sieve shall be thoroughly clean and dry. The magnesia shall be placed on the No. 200 sieve with pan and cover attached, and shall be held in one hand in a slightly inclined position so that the sample will be well distributed over the sieve. At the same time gently striking the side about 150 times per minute against the palm of the other hand on the upstroke. The sieve shall be turned every 2 5 strokes about one-sixth of a revolution in the same direction. The operation shall continue until not more than 0.05 gram passes through in one minute of continuous sieving. The residue on the sieve shall be weighed, and the weight expressed as a per cent of the weight of the original sample. The residue shall then be screened through 100 mesh sieve, using the same method of operation, and the residue on 100 mesh sieve reported. 2 3. Mechanical sieving devices may be used but the plastic magnesia shall not be rejected if it meets fineness requirements when tested by the hand method. IX. Standard Oxychloride Cement Mixture. MIX. 24. F'or the determination of setting time, modulus of rupture, and linear change, a standard oxychloride cement mix shall be prepared as follows : (1 part by weight of plastic magnesia. 2 parts by weight of standard ground silica or silex. 5 parts by weight of standard silica sand. SILBX. 25. The ground silica or silex used shall be ground from a pure silica sand or from quartz. It shall consist essentially of pure silica (SiOo). Ninety-five per cent of the material shall pass a standard No. 100 sieve and 75-85 per cent of the material shall pass a standard No. 200 sieve. SAND. 2 6. The sand to be used shall be a natural sand from Ottawa, Illinois, screened to pass a No. 20 sieve and be retained on a No. 30 sieve. This sand may be obtained from the Ottawa Silica Company, Ottawa, Illinois. CHLORIDE SOLUTION. 2 7. Magnesium chloride solution shall be made by dissolving commercially pure fused, crystallized or flake magnesium chloride in distilled water. The resulting solution shall be adjusted to a gravity of 22° Be. at 60° F. The chloride used shall contain a minimum of 97 per cent MgCl,. 6H,0, less than 2 per cent CaCl,, and less than 2 per cent MgS04. 2 8. Not over 1500 grams of dry ingredients Shall be used for the purpose of an individual mix. The three ingredients shall be thoroughly mixed by hand in a shallow iron or enameled ware pan until a uniform mix is obtained as far as can be told by eye. An amount of magnesium chloride solution, sufficient to bring the mix to normal consistency shall be added, mixing being continued for a minimum of one minute. X. Normal Consistency. 29. For determination of normal consistency a series of consistency pins shall be prepared as follows : MAGNESITE IN CALIFORNIA. 31 APPARATUS. 30. Three pins are required, each being a small cylinder of metal weighing 250 grams and having a flat cylinder face. The No. 18 pin shall have a face 18/16 of an inch in diameter, the No. 16 pin a face of ]6/16 of an inch, and the No. 14 pin a face 14/16 of an inch in diameter. If the pins are made of round bar steel, the No. 18 pin will be almost exactly 2 inches long, the No. 16 pin 2i inches long, and the No. 14 pin 3 7/32 inches long. Tliese linear dimensions shall be taken as only approximate and the weight of the pin in any case shall be adjusted to 250 grams. METHOD. 3.1. For determination of consistency, a pat of the freshly mixed mortar at least one-half inch thick shall be leveled off witli a .spatula to a fairly true surface. The consistency pins shall be gently lowered onto the surface and it shall be noted whether they are totally supported by the plastic mortar or whether they sink into the surface. The desired normal consistency is that at which the Np. 16 pin just fails to make a permanent impression in the plastic mortar. Although it is possible to make determinations by means of the No. 16 pin only, it is far easier to use the No. 14 and No. 18 pins for preliminary adjustment. 32. The amount of chloride required for production of normal consistency with the standard mix given shall be recorded as cubic centimeters per gram of plastic magnesia. 33. An alternative method for determination of normal consistency is that involv- ing measurement of the slump of a 2x4 cylinder of the plastic mortar. 34. A steel or brass cylinder 4" high and 2" in diameter shall be placed on a level surface, filled with the plastic mortar and struck off even. The cylindrical mold shall then be carefully raised in a vertical direction and tlie height of the resultant mass or mortar measured. The mortar shall be considered to have normal consistency when the height of the mass is: (This figure to be developed.) 35. If normal consistency is not attained at the first trial, a fresh batch of dry mix shall be prepared and chloride again added. This process shall be continued until normal consistency is attained with a single addition of chloride. XI. Standard Storage Conditions. STORAGE OF TEST PIECES. 36. All test pieces, whether used for determination of setting time, strength, or linear changes, shall be stored in air at a temperature between 60° and 80° F. XII. Determination of Setting Time. 37. The time of setting shall be determined by the use of standard Gilmore needles. GILMORE METHOD. 38. A pat of standard mix having normal consistencj' about three inches in diameter and one-half inch in thickness with a flat top, shall be made and stored under standard conditions. The magne.sia shall be considered to have its initial set when the pat will bear without appreciable indentation the Gilmore needle one- twelfth inch in diameter loaded to weigh one-fourth pound. The final set has been acquired when the pat will bear without appreciable indentation the Gilmore needle one-twenty-fourth inch in diameter loaded to weigh one pound. In making the test the needle shall be held in a vertical position and applied lightly to the surface of the pat. AUTOMATIC MACHINES. 39. Any suitable automatic setting time machine may be used in carrying out the setting time tests, but the plastic magnesia shall not be rejected if it meets the setting time requirements of the specification when tested by the method described above. XIII. Strength by Cross Bending Tests. FORM OF TEST PIECES. 40. Modulus of rupture shall be determined by cross bending on bars of the standard mix one-half inch thick, two inches wide, and at least ten inches long. • • * Three tests, one at twenty inch and two at ten inch spans, can be made from each bar. 41. The steel base plate and the separating bar of the bar mold shall be oiled slightly with a fairly heavy mineral oil, any excess of oil on the surface being carefully avoided. A suitable quantity of the standard mix shall be prepared, brought to normal consistency and placed in the molds by use of an ordinary plasterer's trowel. The plastic mix shall be brought to the level of the spacing bars with the minimum troweling possible. STORAGE. 42. The bar frames shall be kept in an atmosphere of a temperature of 60° to 80° F. and a relative humidity of 30 to 70. Test bars shall remain in the molds without covering of any kind for from eigliteen to twent.v-four hours, after which time they shall be removed and stored on edge with at least one-half inch air space between bars in the atmosphere specified under standard storage conditions. 32 CALIFORNIA STATE MINING BUREAU. TESTING. 43. Modulus of rupture shall be determined by breaking such test bars by apply- ing- load at the center of a twenty-inch or of a ten-inch span. Any simple cross- bending apparatus may be used. The face of the bar which was undermost i e in contact with the base plate of the mold during preparation of the bars ' shall have the central knife edge of the machine in contact with it. Load shall be applied at the approximate rate of fifteen pounds per minute. The knife edges of the cross bending macliine shall be cushioned by the u.se of thin blotting paper An easily constructed cross bending machine is shown in Plate II herewith. CALCULATION OF MODULUS OF RUPTURE. 44. Modulus of rupture shall be calculated from the applied load by use of the following formula : f= 3 WI 2bh= Where f == modulus of rupture, wrzr load applied. I = length of bar between centers, b =: width of bar. h = thickness of bar. Plate II. -Cross b en ding Testing Machine — For a one-half by two-inch bar, broken by center loading and supported on a tweny-inch center, f = 60 W, or the modulus of rupture is sixty times the applied load. For ten-inch span, f=:30 T\'. 45. Careful workmanship will result in the production of bars differing so little from the standard one-half inch thickness that the factor 60 can be uniformlj' used for calculation of modulus of rupture. The thickness of bars varying from standard dimensions should be determined to the nearest sixty-fourth of an inch, and the proper factor from the table below used for calculating modulus of rupture. Thickness of Bar 35/64 34/64 33/64 32/64 31/64 30/64 29/64 Factor ;0" length 50.2 53.2 56.4 60.0 63.9 68.3 73.1 Factor 10" length 25.08 26.57 28.21 30.00 31.97 34.13 36.53 MACiNKSITI-: IN CM. IFOKNIA. .in 3—39802 34 (lALIPORNIA STATK MININii BUKEAIT. 46. Bars which are manifestly faulty or which give strengths differing more than twenty per cent from the average value of all test pieces made from the same sample and broken at the same period shall not be considered in determining modulus of rupture. XIV. Tensile Strength. 47. For determination of tensile strength, standard briquettes of the dimensions adopted for the test nieces used in determination of tlie strengtli of Portland cement mortars (A. S. T. M. Standards 1921, p. 546) shall be used. TEST PIECES. 48. Immediately after mixing, the standard mortar shall be placed in the molds, pressing in firmly with the thumbs and smoothing off with a trowel without ramming. Additional mortar sliall be heaped above the mold and smoothed off with the trowel. The trowel shall be drawn over the mold in such a manner as to exert a moderate pressure on the material. The mold shall then be turned over and the operation of heaping, thumbing and smoothing off repeated. STORAGE. 49. Test briquettes shall remain in the molds without covering of any kind for from eighteen to twentj'-four hours, after which they shall be removed and stored on edge so that ample air circulation is provided on all sides, in the atmosphere specified under Standard Storage Conditions. TESTING. 50. Tests shall be made with any standard machine. The bearing surfaces of the clips and briquettes shall be free from grains of sand or dirt. The briquettes shall be carefully centered and the load applied continuously at the rate of 600 lbs. per minute. 51. Briquettes that are manifestly faulty or which give strengths differing more than fifteen per cent, from the average value of all test pieces made from the same sample and broken at the same period shall not be considered in determining the tensile strength. XV. Linear Change. TEST PIECES. 5i2. The amount of movement of reference points inserted in a bar of a standard oxychloride cement mix, two inches wide, one-half inch thick, and over ten inches long, shall be determined and shall be reported as linear change. APPARATUS. 53. An instrument for determination of such movement is the Berry Strain Gauge, manufactured by H. C. Berry at the University of Pennsylvania. This instru- ment is shown in Plate III herewith. Instead of the Berry Strain Gauge any suitable optical bench or similar method of measurement which will give true values for the movement of the reference points may be employed. METHOD. 54. Reference points can conveniently consist of small metal pieces of the shape shown in Figure "C," Plate III. Each of these pieces may have on its surface three indentations spaced a definite distance apart. Such indentations can con- veniently be made by the punch shown in "D," Plate III. 55. The linear change test bar should be prepared on a surface covered with waxed paper so that no possible attachment to the surface will result. When the bar is approaching initial set, the two reference points shall be placed in it by the use of the standard length bar of the Berry Strain Gauge. The spacing points on this bar, which are approximately ten inches apart, should be placed in the center of the three indentations in each of the metal plates as these plates are gradually pushed into the still plastic material so that these center indentations are approxi- mately ten inches apart when these plates are placed. 56." The initial measurement shall be made at the time when the test bar reaches final set. Further measurement shall be made at twenty-four hour and seven day age. With a magnesia giving cements which show very little linear change, only the center indentations will be needed, taut if linear change reaches a high value, these center indentations will fall outside of the limit of the gauge and measurements can then be continued with the other indentations, proper addition or subtraction from the gauge readings being made when such change in reference points is made. PRODUCTION AND PRICES. In considering mineral ]n'0(lncti(in, the tonnage and value of the crude mineral is used as far as possible. Magnesite presents a peculiar example of a material which (except during the war-time activity of 1915-1919) was seldom handled on the market in a crude state, it being ordinarily calcined and ground before being sold. By taking the average price of unground calcined magnesite, in sacks, at San .\rA(i.\ESITK IN" rAMFORXIA. ST) Francisco, less freight, and figuring from 2 to 2^ tons of crude to 1 of calcined, on arbitrary value for the crude material at the mine was determined and used in reports of the State Mining Bureau, previous to 1915. On this basis the assigned value per ton was somewhat hiuher than actual contract prices for crude ore, as developed later, when it began to be sold in crude form. Considerable tonnages were shipped in a crude state in 1915, at prices ranging from $7 to $11 per ton f. o. b. rail-shipping point, or an average of about $9 per ton. In 1916 crude magnesite was contracted for at from $6 to $10 per ton f. 0. b. rail-shipping point or an average of about $8 per ton. Prices for 1917 ranged higher, the value of crude averaging about $9.50 per ton. During the height of the summer shipping season, in July prices reached a figure of $12.50 per ton, f. o. b. rail. BetVn-e the close of the year, however, the market broke, due in part to freight- car embargoes and priority classifications, and to the competition of the new Washington deposits. The 1918 magnesite yield of California was reduced more than SO'/f from the 1917 figures, on account of the Washington and Canadian competition. The value of calcined magnesite varies, the San Fraiici.sco price for 1916 ranging from $25 to $-45 per ton. which figure includes about $4 per ton freight. During 1917 it ranged from $85 to* $55; and in 1924. from $30 ^to $35. The July, 1918, quotation at New York was: Raw magnesite f. 0. b. works, Pittsburgh, $30 to $35 per ton : dead burned, per net ton @ $50 to $60. The production of magnesite in California remained ({uite steady for the 5 or 6 years immediately antedating the outbreak of the war, averaging not far from 10,000 tons of crude per year. There was practically no change in conditions in 1914. During that year four counties, Alameda. Santa Clara, Sonoma and Tulare, produced a total of 11,438 tons of which 9650 tons came from Tulare County. In 1915 the output increased to 30,721 tons distributed among six counties. Tulare produced 11,574; Santa Clara 7623; Fresno and Kern 6850, with smaller amounts from Sonoma and Napa. 30 CALIFORNIA STATE MINING BUREAU. The 1916 production of the state wa,s approximately 5 times that of 1915. It totaled 154,052 tons, distributed by counties as follows: Plate IV. i 1 1 if" i " gUo 50,000 ■ 1 \ \ / / \ \ \ / / / 1 \ \ \ y — \, .' ~- 1 >., f \ \ \ / / / ^> - -« '- /» • \ • * "^ 1 t \, - '" / r s \ / / 1 PRODUCTION & AVERAGE VALUE OF MAGNESITE- CALIFORNIA 1887-192+ (iNC) CAUrORNlA STATE M1NIN6 BUREAU Aoompanying Bulletin N®79. 1 1 / 1 / \ / 1 1 _ ■^ __, — ^ / V V i 1887 1890 1895 I9CX3 1905 1910 19IS YEARS Magnesite Production, by Counties, 1916. 'County Fresno Mendocino Merced Napa Santa Clara Sonoma Tulare Alameda, Kern, Placer, Riverside, and Tuolumne* Totals 1'54,05 ' Combined to conceal output of a siiifrle o])crator in each. Tons Value 5,829 $49,082 300 2,400 90 720 1-3,960 108,556 23,207 232,156 11,653 98,280 87,606 737,130 11,407 83.560 $1,311,89: MAGNESITE IX CAIJFOKNIA. 37 Tlie production l)y counties for the record year 1917 is given in the following table, with total crude values : Magnesite Production, by Counties, 1917. County Tons Value Fresno 6,077 $57,422 Nana — 40,329 387,930 Santa Claf^'Z^ZZZZ^l^^Z:^^-^""' 9.963 99.287 Sonoma 5,636 ^A'nll Stanislaus 3,196 44.350 Tulare A_::::::::::::::::::::::----:: 136,562 1,238,853 Alameda, Kern, Mendocino, Placer, Riverside, San Benito, „ „ „ Tuolumne > 1 7.885 87,0o0 Totals -- 209,648 $1,976,227 Californian Production in 1924. The i)roduction of magnesite in California during 1924 amounted to a total of 67,236 tons of crude ore valued at $900,183. Only a small part of it was sold 'crude,' however, as it is practically all shipped in the calcined form. The reports at hand show a total of 29,23-5 tons shipped calcined, of which 2925 tons were dead-burned and sold for refractory purposes, the balance going to the plastic trade. The 192-4 output is a slight decrease both in quantity and value from the 1923 figures of 73.963 tons crude valued at .$946,643. The average of the values reported for 1924 is .$13.40 ])er ton as against $12.80 in 1923. ^ The more important producing i)roperties in 1924 were: iNIaltby No. 1 (Western Magnesite Development Co., operated under lease by C. S. Maltby), on Red ]\Iountain, Santa Clara County; and the Sierra Magnesite Company s group near Porterville, Tulare County ; followed in order, by the Sampson Peak mine (Maltby No. 3), San Benito County; California ^Magnesia Company (old Harker mine) at Porter- ville ; and Maltby No. 2 in Chiles Valley, Napa County. Lesser amounts were reported mined in Fresno and Stanislaus counties. Total Magnesite Production of California. Tlie first commercial production of magnesite in California was made in the latter part of 1886 from the Cedar ^^lountain district,- southeast of Livermore, Alameda County. Shipments amounting to 'several tons' or 'several carloads' w^ere sent by rail to New York; but there is appar- ently no exact record of the amount for that first year. The statistical records of the State Mining Bureau began with the year 1887, and the table herewith shows the figures for amount and value, annually, from that time. Shipments of magnesite from Napa County began in 1891 from the Snowflake Mine; from the Red ^Mountain deposits in Santa Clara County, in 1899 ; and from Tulare County in 1900. • Combined to conceal output of a single operator in each. = See U. S. Geol. Surv. : Min. Res. of U. S., 1886, pp. 6, 696. 38 CALTFORNI.V STATE jriNIXG BTTREAU. Production of Magnesite in California, Since 1887. Year Tons Value Year Tons Value 1887 1888 600 600 6C0 600 1,.500 1,.500 1,093 1,440 2,200 1,500 1,143 1,263 1,280 2,252 4,726 2,830 1,361 2,850 3,933 $9,000 9,000 9,000 9,000 15.000 15.000 10,930 10,240 17,000 11,000 13,671 19,075 18,480 19,333 43,0.57 20,655 21,515 9,298 16,221 1906 1907 _-.._- 4,032 6,405 10,5.82 7,942 16,.'>70 8,858 10,512 9,632 11,438 30,721 1.54.0.52 209,048 83,974 44,696 83,695 47,837 55,637 73,963 67,236 $40,320 57.720 1889 190S 80,822 1890 1891 1909 1910 - . 62,588 113,887 1892 1893 1911 1912 1913 1914.. . 67,430 10.5,120 1894 _. 77,056 1895 114,380 1896 1915 283.461 1897 - - 1916 1,311,893 1898 1917 1918 1919 1,976,227 1899 803.492 1900 452,094 1901 1902 1903 1904 __ __ 1920 1921 1922 1923 1924 1,'!33,491 511,102 594,665 946,643 1905 900,183 Totals 970,701 89,828,049 The chart (Plate IV) shows graphically the total annual tonnages and the average annual values per ton of the crude magnesite. Since 1906, the variations in the price per ton of magnesite have been pro- portionately small. Though the demand and resulting tonnage output increased many fold in 1916 and 3917, there was not the same propor- tionate increase in the price per ton as was the case with such minerals as chromite and manganese ores. TARIFF and IMPORTS. Prior to 1922, there was no nistoms duty on the importation of foreign magnesite into the United States. Material for refractory pur- poses (mainl}' dead-burned) was received from Austria-Hungary; and plastic magnesite was received mainly from Greece. In 1924, imports from India became a factor in the plastic market. The Tariff Act of 1922, which became eft'ective September 22d of that year, placed the following import duties on magnesite : Crude magnesite -iyA V^^^ l^J- ; caustic-calcined magnesite Hs^ P^'^" 1^- '■> dead-burned and grain magnesite, not suitable for manufacture into oxychloride cements 23/40f per lb. ; magnesite brick, "{f per lb. and 10% ad valorem. The following tabulation shows the amount (short tons) and value of magnesite imported 'for consumption' into the United States for the years 1912-1921: Year Crude Calcined, not purified Tons Value Tons Value 1912 17,905 13,240 13,354 49,765 75,345 30,277 5,4.32 6,381 33,550 51,993 73,331 5,182 6 $101,326 84,911 .54,677 2.55,140 634,447 232,105 103,2.33 103,311 406,204 .525,' 52 976,283 44,081 85 125,252 167,094 121,817 26,. 574 9,270 3,966 19,049 9,476 14,780 6,788 72,265 72.955 64,785 81,265,339 1913 1,672,565 1914 .. .._ ;,.323,194 1915 232,071 1916 .. 204,183 1917 _.- 2.32,601 1918 ... 824,022 1919 ._ 270,721 1920. 373,165 1921 ... . .. 250,9.32 1922 ...... 1,267,622 1023 ... . ... 1,022,968 192^ 1,172,403 MAGNESITE IN CALIFORNIA. 39 Duriiii^' till* hearings l)et'oro tlu' \Va\s aiul Means Coimiiittee of the House and the Finance Counnittee of the KSenate when the matter of a magnesite tariff was pending in 1921, many valuable and interesting data were brought out, as to the relative (|uantities and the comparative value of the American and foreign magnesites both refractory and plastic; also regarding costs of production. It was shown that prior to the war, calcined, refractory magnesite was imported from Austria at a cost of $15.75 per ton, the cost at the mines in that country being about $7 per ton. The railroad rates and dock charges amounted to about $2 per ton and the ocean rates to Atlantic ports were about $2 per ton. The average cost of that produced in the United States was shown to be about $25 per ton at the mine, and the freight is from $10 to $16 per ton depending on destination. The bulk of the con- sumption of refractory magnesite in the United States is at the center of the steel industry (Pittsl)urgh and vicinity), as only 5.7% of the npen-hearth steel furnaces of this country are west of the Mississippi River. West of the Mississippi there are 129 copper converters which would require only 2.8% of the dead-burned magnesite consumed in the United States. In 1920, a total of 35,000 tons of plastic magnesite was utilized in the United States. "Prior to the war, the plastic business was insignificant. There was practically no plastic business. Tlie architects all over the United States were opposed to the use of magnesite. The foreign magnesite was unreliable. Sometimes we had a good job and sometimes a bad one. With reference to exterior stucco in 1914, 4,000 houses were covered with it. Last year (1920), due to the fact that we were able to oljtain a high-grade magnesite, we covered 40,000 houses with material of this kind made from American magnesite. * * * "v^e favor a duty because the Grecian magnesite which is mostly used for plastic purpo.ses is not uniform. It is not up to the standard." ' In 1924, in spite of the tarifl', importation.s of plastic magnesite from India reached a point in tonnage where they seriously affected the market for the Californiaii product. BIBLIOGRAPHY. CAL. STATE MIX. BUR. Reports VI, XII, XIII, XIV, XV, XVII- XX (inc.) ; Bulletins 70, 71, 74, 83, 86, 88, 90, 93, 94, Mineral Produc- tion for vears 1914-1923 (mc.) ; Buli. 91, Minerals of California, 1923. ECKEL, E. C— Cements, Limes and Plasters, 1905. EXG. SOC. WESTERN PENNSYLVANIA, Proc. vol. 29, pp. 305- 338. 418-444, 1913. JOUR. A:\IER. CERAMIC SOC, Vol. 3, No. 3, pp. 185-246, Mar. 1920: 'Magnesite Refractories,' bv J. S. .McDowell and R. :\I. Howp. SEATON, M. Y.— Proc. Am. Soc. for Testing Materials, Vol. 21, 1921 ; Chem. & Met. Eng., Vol. 25, No. 7, Aug. 17, 1921 ; Chem. Age, Vol. 31, pp. 17-22, Jan. 1923. THORPE, T. E.— Outlines of Industrial Chemistrv, li)09. U. S. GEOL. SURV. PUBLICATIONS: Bulletins 355 and 540: Min- eral Resources of the U. S. 1913, 1915. ' Hearing before the Committee on Finance, U. S. Senate, on H. R. 74.56, Aug. 27, 1921, p. 2078. 40 CALIFORNIA STATE MINING BUREAU. . ^ '?•. . • ' <. "'• .• -g^iifc'--*'— **n ^M ^■*^gSlk-- ''".i"" J*-' ■ ^SV-^V^^^JflmgL "-^^^^^IdBiC ^-^ m^^' ^^^^^^^^^^^^^H|p'^< ''"^^''^^dJUSSHHlii '^^■^ ^' -''^^ ''^^'iiL** .■mi . _■ \ ^4 ■ .-"">'-,-*'- ... -' '" '..-x ■" '' ' J '■'" Photo No. 6 — Cedar Mountain Mag-nesite Mine. (The glory liole is on Uie liill above the large dump.) F- > te -'^.'/t^'--/ . - , -Ij ■ tV „» -.' »_ * M ^3 ^P- 1 wBm -.^^1 WE?^" ;■: B mI PM„; .:--;.^ Photo No. 7 — Open cut (glory liolc) m Cidai- .Mountain Magnesite Mine. MAGNESITE IX CAIilFORNIA. 41 Californian ^Fixes and Plaxts. ALAMEDA COUNTY. ]\Iao:nesite was mined in Alameda County as early as 1886 ^ the deposit being located on Cedar Mountain about 13 miles southeast of Livermore. The magnesite occurs in a decomposed serpentine rock and in a yellow clay in which are imbedded large boulders. It lies in pockets and small veins, the latter running in all directions. Several of the deposits have been exhausted and only one property was worked to any material extent. ]Magnesite croppings and con- siderable float have been found in Rocky Ridge, west of Cedar Moun- tain and separated from it by the Arroyo del Valle, but no large deposits have yet been uncovered. Cedar' Mountain Magnesite Mine is in Sec. 27, T. 4 S., R. 3 E., ]\r. 1). y\.. at an elevation of :>2r)()' above sea level. It was worked spasmodically for several years, and in 1917 and 1918 Avas being operated under a ten-year lease by J. W. Clark and D. ]M. McDonald of Livermore. Over 2000 tons of magnesite were shipped from this deposit in 1916, and about 1160 tons sold to the Hoff Asbestos Company, Oak- laiul in 1917. This latter brought from $12 to $14 per ton. Very little work has been done since 1917; and there is at present (IMay, 1925) about a carload of ore on hand ready to ship. The magnesite from this deposit is, as a rule, of excellent quality. There is a series of small magnesite outcrops running east of north and dipping eastward. Wherever these croppings have been uncovered or dug into they show up as tops of lenses of magnesite which widen out below the surface. The largest lens Avas developed by a glory hole and cut. A tunnel driven 10 feet below the ])ottom connected with a chute, through which the ore was handled. This pit measures about 30 feet across and 30 feet deep. A drift driven from the main tunnel southward 50 feet failed to cut an orebody. Work has also been done on several croppings to the north of the glory hole. This property is equipped with an oil-burning flat-hearth-type funiace. built by S^nndell (lessee in 1914) designed especially to jiroduce 'dead-burned' magnesite, with a capacity of 5 tons of cal- cined material per 24 hours. Tliis furnace has not been used since Swindell worked the mine in 1914. It is said to have produced a very uniform burn, but its cost of operation was higher than that of shaft furnaces, as it required more labor to operate, and its fuel consumption was greater per ton of magnesite calcined. The present lessees reopened this mine during the summer of 1917 and up to December, liad ship]>ed several hundred tons of crude magnesite, mainly to the Iloff Asbestos Company in Oakland. Five men were employed in the development work. Water for camp pur- poses is obtained from a well on the i)roperty. The area of the holdings is 160 acres. IM. 1. Crocker. 1023 In.surance Exchange Bldg., San Francisco, owner. Bihliof/rapln/: V. S. ({e.il. Surv.. P.mII. 430. p. 173. IIMO. ' U. S. Geol. Survey. Miii. ]lv!-\ i<( the U. S., l.'Si>f., pp. li, G'JG. 42 CALIFORNIA STATE MINING BUREAU. Hayes Ranch Deposit. Some .small eroppiugs of buff-colored iiiagnesite occur in the S\V] of Sec. 24, T. 4 S., K. 2 E., M. D. M., about 11 miles southeast of Livermore near the summit of Rocky Ridge. Some large bouldei-s of pure-white float are lying in a ravine north of and below the outcrop. Several tunnels were driven into the hill under these boulders in hopes of striking an orebody but none was encountered. On the east slope of the ridge numerous boulders have been found. Cuts have been made along the slope Photo No. 8 — Plat-hearth calcining furnace at Cedar Mountain Magnesite Mine, Alameda County. at several places in all of which boulders of high-grade ore have been found. It is possible that these boulders are in place, being formed as a gradual replacement of serpentine ; however, considerable development would be necessary to determine this. About 25 tons of magnesite are lying on the dumps. There has been no rock .shipped from this prospect and it is idle. An old wagon road from Livermore gives easy access to the property. Winship Properties. K. D. Winship, 350 Post Street, San Fran- cisco, owner. J. W. Clark and D. McDonald of Livermore as lessees, MAGNESITE IN CALIFORNIA. 43 in 1917 did some prospecting and development work on a series of magnesite outcrops on this property in Sec. 20, T. 4 S., R. 3 E., about one mile east of tlie Cedar Mountain mine. In the SAV] of Sec. 85, something over a mile southwest from the above, there is a considerable body of serpentine Avhieh extends west- ward at least as far as the center of Sec. 34 adjoining. In this area, near the north-central part of the SW^ of Sec. 35, there is a small but promising looking outcrop of magnesite. In the serpentine area there are also patches of pellets (see Photo No. 9) and occasional veinlets of hydro-magnesite (a soft hydrous carbonate of magnesia). Some of the larger of these patches were at one time worked at the 'magnesia mine' in Sec. 34. As these sections lie in a rather deep canyon, a branch of the Arroyo del Valle, transportation out Avould be difficult and expensive. ^--^.-^i"^- Photo No. 9 — PelUHs of hvdro-magnesite in serpentine in Sec. 34, T. 4 S., R. 3 K., M. D M., Alameda County. 44 CALIFORNIA STATE MINING BUREAU. FRESNO COUNTY. The production of magiicsite in Fresno County began with a few tons in 1904, and the total recorded yield to the end of 1913 was 5643 tons. The ontpnt in both 1916 and 1917 exceeded the total production up to and including 1913. For 1917 it amounted to 6077 tons, valued at $57,422. The properties so far developed are all located in a small area near Piedra, the terminus of the Reedley- Piedra branch of the Santa Fe railroad, about 25 miles east of Fresno. John Anderson. The property of John Anderson of Piedra is reported to contain deposits of magnesite, but the extent and import- ance of the occurrence has not as yet been determined. Ferguson Mine. (See Sample Mine, also Sinclair Bros. Plant.) Piedra Magnesite Company (formerly Fresno Magnesite Mine; known locally at one time as Bachler). This property embraces 40 claims which' lie mainly in Sec. 5, T. 13 S., R. 24 E., I\I. li. M. The main workings are on the north side of Kings River within one-half mile of Piedj-a, the railroad shipping point, and expensive hauling charges are avoided. The Fresno IMagnesite mine Avas one of the first to be Avorked in Fresno County, and it has furnished the greater part of the output to date. The magnesite occurs in a series of veins in serpentine. These have been operated by tunnels. A Avinze sunk 40 feet beloAV the loAA'er tunnel level is said to have shoAvn 30 inches of magnesite at the top and 14 inches at the bottom. This shoot Avas approximately 114 feet long. The former oAvners, ^I. F. Tarpey et al., of the Fresno Magnesite Company, sold to the Piedra Magnesite Company late in 1917, Thos. J. Curran, Porterville, manager. That company installed a 50-ton rotary kiln alongside the railroad at Piedra, AA^hich displaced the old stack furnace of 25 tons daily capacity at the mine. The property has been idle since 1918. Bibliography: Cal. State Min. Bur., Report on Mines & Mineral Resources of Fresno Co., July, 1915 ; also Report XTV. U. S. Ceol. Surv., Min. Res. 1917. p. 67. Piedra Mine (also knoAA^n as Ward). The Piedra Mine is located in Sec. 9, T. 13 S., R. 24 E., M. D. M. It lies south of the Fresno Magne- site mine and has equal, if not better, shipping facilities, being on the south side of Kings River aboA^e the railroad tracks. A short gravity tramAA'ay Avould land the material at the railroad. The property lies on the rounded north face of a hill Avhich sup- ports the groAA'th of a fcAv scattered oak trees. The magnesite occurs as veins in peridotite and is of No. 1 grade, carrying 98% MgCOo, 1.2% SiO. and 0.6-0.8%- CaO. A cro.sscut adit 155 feet in length cuts a 4-foot vein striking N. 65° E. and dipping 80° N. The tunnel has exposed the vein 20 feet beloAv the surface outcrop, Avhich is over 225 feet in length. Another adit crosscuts a parallel vein at 40 feet and folloAvs it for 80 feet. This vein averages 30 inches in Avidth, strikes N. 50° E., and dips 85° N. The 8-foot vein described in earlier reports^ narroAved to about 4 feet at a depth of 14 feet. ' Bradlev. AV. AV., Mines and Mineral Resources of Fresno County : Cal. State Min. Bur.. Report XIA', p. 455, 1915. MAGNESITE IN CAl.IPORNIA. 45 Jj. F. Ward, Oakland, California, owns the mine, which has been operated by various leasers. In part, the ore has been shipped crude; and in part, calcined in the furnace of Sinclair Bros, at Piedra, just below the Ward mine. The latest operations were in the summer of 1924, when a small tonnao;e was taken out ])y Wm. Clear}^ lessee, and calcined at Piedra. Dr. Powers had a lease in 1917 on the magnesite property of Mrs. Snyder, located east of the Fresno ^lagnesite mine, near Piedra. Two Photo No. 10 — Magnesite calcining furnace of Sinclair Bros. (Ferguson), at Piedra, Fresno County. Capacity, 25 tons of- crude ore per day. men were then working on a small vein, but nothing has been done since. Sample Mine. This mine owned by W. C. Sample, is on Holland Creek south of Academy, and is leased to A. ]). Ferguson, 2975 McKonzie Ave., Fresno. Ore from tliis mine was hauled (1922 and 192."?) to the calcining plant of Sinclair liros. (bought by E. E. Fergu- son, son of A. D. Ferguson), at I'iedra, 11 miles by truck. Ferguson reports having shijjped many carloads analyzing as low as 0.4% CaO. Silica was as high as 2()'.i, l)ut not ol)jectionable as the product was used for plastic purposes, idle in 1924. 4(5 CATJPORNIA STATE MINING lUTREATT. J. B. Siebert, address Sanger, star route, has four claims above the Fresno Magnesite mine from whieh one car of ore was shipped in 1916. The material had to be sorted at Porterville and he r<'eeived only .$100 for the lot. ■Sinclair Bros. Plant. This i)lant (M))itaining a stack kihi witli capacity for handling 25 tons of crude magnesite i)er day Avas l)uilt by Sinclair Bros, in 1918. It was sold to E. C. Ferguson in 1922. This furnace has been utilized for calcining ore mainly from the Ward mine near by and the Sample mine south of Academy. Sinclair informed the writer (in 1920) that by careful temperature regulation, using an electric pyrometer, they obtained caustic magnesite at 800°-900° with not to exceed 4% CO. remaining, yielding "a more active MgO." R. S. Snyder has a showing of magnesite on property adjoining and east of the Fresno Magnesite mine. Wm. Terrill, in 1917, had a lease on a magnesite property located 3^ miles northwest of Piedra. Vance property. The Vance holdings consist of four claims situated about six miles north of Piedra. Some development work was done in 1917. MAGNESITE IN CiAT.IFORNIA. 47 KERN COUNTY. A new type of deposit of! magnesite was developed in Kern County in 1911, and shortly afterward was first described by Gale ^ in part as follows: "The deposit is situated about one-li:iIf to three-quartei s of a mile northeast of Bissell Station. The only developments tliat had been made up to March 8, 1'j12, consisted of a series of pits and a few shallow shafts opening the deposit tlirough a stretch of about a quarter of a mile. "This deposit is unique in being the only occurrence of magnesite of evident sedimentary origin that lias been reported in tliis country. Some deposits in Quebec are described as probably of sedimentary origin, but liitherto all tlie Cali- fornia magnesite lias been described as associated with and evidently derived from altered basic intrusive igneous rocks carrying a large percentage of magnesia. "The magnesite at Bissell occurs in definitely bedded form, interstratifled witli clays and clay shales, and evidently forming a part of the same series tliat shows massive ledges of limestone and chert.v layers in outcrop near by. The clay beds are prevailingly dull greenish ))ut in places consist of a very dai'k carbonaceous material. In the low rounded hills that characterize this part of tlie Mojave Desert the strata in general do not outcrop conspicuously and consequently are not readily traced. The limestone and cherty ledges are visible, however, and recent prospect- ing has revealed the softer magnesite-bearing beds to some extent. The outcrops piospected occur on the south slope of a low ridge. Photo No. 11 — General view of Bissell Magnesite Mine, looking eastward. "The magnesite can be obtained in very clean white masses, as it readily separates from the inclosing clay. It is pure white, very fine grained, and compact, breaking with a china-like conchoidal fracture, such as is characteristic of most magnesite. On e.x-posure to the air, however, the material from tliis deposit shows a tendency to break down that has not been noted at other deposits. A rain a short time before the date of visit had wet the magnesite on the prospect dumps and the lumps were said to ha\'e cracked and broken down like lime starting to slack. It was observed that only the more freshly dug material afforded solid specimens. Disintegration by weathering may give to the surface of these deposits a some- what coar.ser and more earthy textmc than tlic porcelain-like fracture characteristic of magnesite, but the inck has nevertlieless a marked similarity to the typical magnesite. It would perhaps l)e surprising if a sedimentary deposit of this sort should be found to cairy as low a iiercentage of lime as is contained in many of the other California magnesite.^. "All other California niagnesitf (If)iosits, so far as known, occur as veins in conniction with serpentinized magnesia n rocks, iisuall.v refeiTcd to as serpentines. No exidence of any assrxiation with Sfi-piMit hies was observed at the Bissell deposits. ".V sugestion as to the possible origin of the.se deposits may be found in con- sidciing the charactei- of the salines conmionly associated with the lake-bed deposits of the desert basins. Magnesium is commonl>- ab.sent from the soluble salts of the desert-lake salines, although magnesimu .salts are common constituents of spring Bull. 'Gale, H. S., Magnesite deposits in California and Nevada: U. S Geol Survev 11. 540, pp. 512-516, 1914. " '='"'*'^^' 48 (!ALIFf)RNIA STATE MININ' ' ^ ' ^ ^ ^^^ V '^ - \ /. ^V . '.^^t^^^\ ^ ^ ^ V - " V ' < CLAY magnesite: /OO - ft LEVEL Ca/ifornia Sfaf'e M/n/^ig Bureau. Accompanying Bu//et/n /V- ^S lime in the resulting precipitate. It is alsn suggested that if this magnesite were thus precipitated, it would probably Ijo in part at least, laid down as hydro- magnesite, and that it would have been deposited more thickly near the source of supply and thus the beds would necessarily be lenticular." The Bissell deposit lias l)eon extensively developed since the report to which we arc indebted for the above extracts was published. There MAGNESITE IN CALIFORNIA. 49 is an open cut 2200 feet in leiiiith Avitli a iiiaxiiinun depth of 30' and two shafts, No. 1 and No. 2. One shaft has reached a de])th of 100 feet and from the bottom a drift Avas run west 400 feet, and another east 200 feet, and a series of raises put up cutting the different sti'ata. The ma.miesite occurs in beds with clay, clay shales and limestone, striking from N. 60° AV. to N. 85° W., and dipping from 25° to 45° S. Some of the shale strata are somewhat sandy. The magnesite strata vary in thickness from mere seams up to beds 4 feet in thickness, the major portion running from 8 to 18 inches. On the west end the orebody is cut off by a fault running NE. The accompanying clays and limestone are magne- sium bearing. There is considerable fraginental chalcedony in the Photo No. 13 — Bissell Magnesite deposit, sliowing stratificati claims in Sec. 26, T. 2)^ S., K 15 E., Monterey Connty, east of Tarklield. When visited by the writer in September, 1{)17, work in several open cnts to a maxinuim depth of 'M)' had developed a series of 'bonlders' or segregations in serpentine. Shipments totaling 100 tons of calcined material were made during the summer of 1917 ; and there was approximately 300— 1€0 tons of crude ore, in sight, when they shut down for the winter. Calcining was done in the 10-ton Scott, fine-ore. quicksilver furnace of the Kings Quicksilver mine described by Bradley^ (see Photo No. 14), using oil for fuel. The operators stated that, while this I'noTi) No. 14 — Scott, fine-ore quicksilver furnace at Kings Mine, Kings County, used for calcining magnesite. furnace would hold 14 tons of magnesite, their avc^rage was 8 tons burned per day. The ore was crushed to pass a 1-inch grizzly before charging to the furnace. Calcining of fine ore proved successful in this furnace. (See also Western Magnesite Development Company, in Santa Clara County, post). Consumption of oil amounted to 2h bbl. per 24 hours, and cost (1917), $1.45 i)er bbl. at Cholame, and $2.75-$3 at the furnace. The cost of hauling the crude ore from mine to furnace was $1 per ton. The calcined product was hauled by motor truck to the railroad at San ^liguel (about 40 miles). There have apparcntlv been no shipments of maenesite from this pi-opcrlx' since 1917. ' Bradlev, W. W.. Quicl, pp. 516-519. 62 CALIFORNIA STATE MINING BUREAU. divide tjetweon tlie valley in whicli the town of Wiiicliester is situated and Diamond Valley, on the south. The mine is aliout two miles in an air line from the nearest point on the railroad and is four miles by g-nod road from the shipping point at Winchester. * * * The open cut of the magnesite mine is about 500 feet above the level of the plain at the vallev margin. * * * iphe property all lies within the NW.^ of See. 31, T. 5 S., R. 1 W., S. B. M. "The area is g'eolog'ically somewhat complex. It consists essentially of dark banded micaceous gneisses and schists in which the foliation trends in general from northwest to southeast, and dips steeply to the northeast. * * * Probably Intrusive into the micaceous .gneiss is a belt of serpentine from 200 to perhaps 400 yards wide, extending in a northwest-southeast course from a point near the northwest corner of the section. * * * "Many pits on this property expose networks of thin veins of magnesite in serpentine rock decomposed in place. The principal deposit of this sort is that shown in a large open cut crossing the summit of tlie ridge at its north end and making a prominent landmark visible for miles through the valley on the north. This cut is about 85 yards long and some 2 5 yards wide at its widest place and is entrenched to a depth of 60 to 75 feet in the crest of the ridge. Dumps have been thrown out at both ends and from this cut all the magnesite shipped has been taken out. The cut shows a network of magnesite veins throughout, these being fully as numerous and of as great individual thickness at the present bottom of the pit as they were near the top, or possibly the size and thickness of the veins are even increasing with depth." An analysis of a representative sample of the material as mined, made up of thirty portions collected in various parts of the cut, is given by Gale ^ as follows : SiO. 6.17% AlO, Fe..O,, .80% Cab Trace MgO 4 3.80% CO. 45.02% Undetermined 4.14% 100.00% Quoting further from the same author : "The following average taken from a mill run shows the composition of the product ground for plastic use, as it is barreled for shipment. * * * Insoluljle 14.00% Iron and Alumina .80% Calcium Oxide .61% Magnesium Oxide S4.'59% 100.00% "The recoverable and available magnesite veins possibly constitute one-tenth of the mass, although the actual proportion of magnesite in the finer form may be considerably highei". Thus eight to ten or more wheelbarrow loads of waste go over the dump for one load of magnesite saved. There is much fine magnesite in the dump, and it has been suggested by the owners that this might be utilized directly in the manufacture of brick. * * * "The deposit at Wincliester presents several features that might be considered almost unique. In tlie first place the rather exceptionally favorable situation of the deposit for mining, and also for shipment, gives to it a distinct advantage. In many other situations it would doubtless be impracticable to mine, separate, and ship magnesite occurring in a network of thin veins traversing a massive body of serpentinous rock. As stated, the whole mass is so deeply weather-decayed that it breaks down easily and is mined by open cuts with some blasting, the ore and waste being worked over by liand labor, with pick, shovel and wheelbarrow. How- ever, the magnesite readily separates from the much decomposed country rock, crumbling away as dug, leaving the fragments comparatively clean to be sorted by hand. * * * xhe situation of the deposit at the crest of a steep slope is an important factor, as it affords a ready dump for waste and convenient sites for ore chutes and loading bins. The mining methods are therefore of the simplest type." The same author mentions that "the entire product of the mine at Winchester is manufactured into cement or is sintered for furnace use at the company's plant in Los Angeles." The report from which the above excerpts are taken was made in 1912. Since then the Hemet magnesite mine has been under the control of a number of ditferent parties. Extensive development work has been carried on and a new and complete calcining and grinding plant has been erected at the mine to replace the Los 3 Op. cit., p. 51S. MAGNESITE IN CAIJFORNIA. 63 Angeles plant, which was abandoned. Mining is done by open cut and glory hole. A tunnel has l)een driven N. 60° E. in the main quarry floor to cut the deposit through drifts along the orebody Photo No. 19 — General \ie\v of the lit-uiei Magno.siio ^Nline luuking westward from the top of the hill across the Hemet Valley. Riverside County. The large open cut at extreme right shows stockwork of magnesite veins throughout its length. The calcining and crushing plant is housed hi the building below the tramway. Photo by C. A. Waring. Photo No. 20 — Hemet Magnesite Mine looking eastward, showing dumps, and sort- ing and washing plant at head of 400-ft. gravity tramway which conveys the ore to the calcining plant. Photo by C. A. Waring. running N. 40° "VV. The south drift connects by a chute with the glory hole 50 ft. below the toj), and a raise in the nortli drift has been put up to tap the glory hole. The latter gives backs of 7') ft. Drifting will be continued southeast to determine the length of the orebody. It was the intention of the operators to glory-liolc Hie entire top of the hill. Black powder was used for blasting. 64 CALIFORNIA STATE MINING BUREAU. Surface equipment includes iiieclianical conveyors, screens, washers, a 6' X 60' rotary kiln, grinders and packing house. The ore is first carried hy a system of belt conveyors to a sorting room containing a picking belt '>W long by 3' wide. TAvelve pickers are employed and each sorts out about 1500 lbs. of magnesite per shift. The material is then conveyed to a screen where it is washed and the fines rejected. AVater for washing is pumped from the valley below the mine. All material passing through 4-inch openings is rejected as it is impossible to hand sort the finer stuff. The washed and screened magnesite is burned in the 6' x 60' rotarv calciner and Photo No. 21 — Outcrop of INIagnesite at tlie Sampson Magnesite Mine. San Benito County. An idea of its size may be gained from tlie standing figures. Plioto by John D. Hoff. then distributed to cooling bins by a drag conveyor. It is finally ground in Sturtevant buhr-emery mills to pass 100-mesh and packed for shipment. It may be noted here that no mechanical means for concentrating the magnesite or effecting a separation of the mineral from the waste rock has so far been found. Various tests, including electro- magnetic separating machines, did not prove successful, and as hand picking or sorting must necessarily be used a great deal of the finer magnesite has to be thrown on the dump Avith the Avaste. MAGNESITE IN CALIFORNIA. 65 Daily production was 30 tons, of calcined magnesite per 24 hours, being the capacity of the kiln. Electric power is used. A total of •'!.■) men were employed, at the time the property Avas visited. The Hemet magnesite mine was last operated hy the Welman- Lewis Co., Hibernian Bank Kklg., J^os Angeles, for Innes-Speiden & Co., Inc., of New York, lessees; but there has been no production since 1919. INIagnesco Refractory Company, owner, Los Angeles. Bibliography: Cal. State Min. Bur., Reports XV, p. 579; XVII, pp. 327-328. IT. S. Geol. Surv., Bull. 355, pp. 38-39 ; Bull. 540, pp. 516-519. 6—39802 66 CALIFORNIA STATE MINING BTTREAU. SAN BENITO COUNTY. Bonanza Quicksilver Mine. The occurrence of magnesite is reported on the claims of this quicksilver group, in Sec. 29, T. 18 S., R. 12 E., U. D. M. near Hernandez. Undeveloped. Maltby No. 3 Mine (see Sampson Mine). Jerome Magnesite Group (sec Standard Group). Sampson Magnesite Mine (Maltby No. 3 Mine). This property comprises a group of 21 claims, of which three had been patented and three were in process of patenting in October, 1917. The mine lies in Sees. 34, 35 and 36, T. 17 S., R. 11 E., M. D. M., 40 miles by road west of Mendota. the nearest railroad station. The magnesite occurs on the summit of a high spur running westerly from Sampson Photo Xo. 22- -South open-cut of Sampson Magnesite Mine. Octobei- 2, 1917, before installation of aerial tram. Peak, and lying between two forks of Larious Creek at an elevation of 3900 feet. The outcrop of the principal body originally covered from two to three acres and consisted of massive crags of white magnesite (see Photo No. 21), which have since been quarried off. It is 500' in length and appears to strike N. 70° E. Gale ^ in his report on this property said: "If the deposit continues in depth with horizontal dimensions corresponding to those at the surface, it is of immense size." Numerous small croppings are found on the ridge below the main deposit. The orebody was early worked in two main open cuts. The 'North Cut' when visited in October, 1917, was approximately 25' high, and 50' deep, with the magnesite showing in a less shattered condition 'Gale, H. S., Magnesite deposits in California and Nevada: U. S. Geol. Surv.. Bull. 540, page 505, 1914. MAGNESITE IN CAIJPORNIA. 67 Photo No. 2 3 — Quarries and ore-bins of Sampson Magnesite Mine, taken fi'om aerial tram, November 8, 1923. I'lioTo No. 21 — Main ■ji. n lut at Sampson (.Maltb.\ No. 3) Magnesite Mine, near New Idi-ia. San Henito County, November, 1923. 68 CALIFORNIA STATE MINING BUREAU. than nearer the snrfaee. Tlie 'South ("uf (see Plioto No. 22) was on the southerly side of the ridge opposite the North Cut. In October, 1917, the ore was being hauled in four-horse wagons about a mile down a rather steep road to the calcining kilns (see Photo No. 25) in the canon of Larious Creek. Later, an aerial tram M^as installed. Three vertical kilns were built in 1917, Avith an average capacity of 16 tons of calcined magnesite each, per 24 hours. Later three more were added. Crude oil was used for fuel, and it is stated that less than 1 bbl. was consumed per ton of calcined magnesite produced. As may be noted from the photograph (No. 25) these furnaces were much shorter than the shaft-kilns usually built for calcining magnesite. No. 1 furnace (nearest to the camera) was 7 ft. in diameter. No. 2, 6' 6" diam. and No. 3, 6' diam. The interior Photo No. 25 — Calcining magnesite in vertical kilns, at Sampson Mine, October, 1917. fire-box construction is shown in Photo No. 26. They were built of common brick, lined with fire-brick; and equipped with 6 burners to each kiln. Air atomizers were used, the air being supplied by a blower driven by a distillate engine. There was a duplicate blower- set for use in case of a break-down. Up to September 25, 1917, something over 1000 tons of calcined material had been shipped, stated to average less than 3|% SiOa; 2|% CaO; 2% CO.; and between 2% and 3% Fe^O^. Analyses of the first two carloads of the cnlcined magnesite shipped are given as follows : No. 1 SiOa 1-17% Fe and Al 1.20% CaO 1-99% MgO 91.60% Ignition loss 3.85% No. 2 1.76% 1.94% 2.00% 92.16% 2.14% MAGNESITE IX CALIFORNIA. 69 Photo No. 26 — Interior of vertical magneslte-calcining furnace of Hoff-Price Company, at Sampson Mine, under construction, October 2, 1917. [^- »VU. I'HOTO X' 27 — Caleiniiii; il i III i,{ Milii;. ,\.. :; (Sampson) Miikh' site Mine, i>ro- liucing dead-burufd refraelory nmgnesite, November, iy2o. 70 CALIFORNIA STATE MINING BUREAU. Tile material was hauled in motor trucks to the railroad at Mendota, (some has l)een sent via Tres Finos), at a cost of $7 per ton. In October, 1917, there were 75 men on the pay-roll. The furnaces were operated by three 8-hour shifts, and the mine by a day-shift crew only. This mine, the past tlii-ee years, has been operated under lease by C. S. ]\Ialtl)y. The six vertical kilns formerly in use at this mine have ])een replaced by a rotary furnace 7' by 80' (see photo), operat- ing at li minutes per revolution. It is oil-fired and Avhen last visited by the writer (in November, 1928) was producing 85 tons of dead- burned refractory magnesite per 24 hours. From 45 to 50 men are employed. The ore is crushed' to ^-inch mesh before charging and 2^ tons of crude ore are required for 1 ton of calcined. Steam power is used. Fuel oil is obtained from the pipe line of the Associated Photo No. 2S — Rotary kiln at Maltby No. 3 (Sampson) Magne.site Mine, San Benito County. Oil Company at IMendota, there being a pumping station on the line at that point. The calcined ore is hauled by trucks to the railroad at Mendota. As the orebody is on top of a ridge, the ore is broken by quarrying operations, and carried to the furnace by a Painter aerial tram, 5000 feet in length, having 16 buckets and being gravity operated. Jack-hammer drills are used in the quarry. The com- pressor is driven by a 4-cylinder gasoline engine which formerly did duty in a Packard automobile. A chemical lal)oratory is maintained at the mine, for technical control of the furnace i)roduct. Analyses are daily made for SiO^, CaO, loss on ignition, and for Fe^.Oa -|- ALO.. + MnO. combined. In 1924, a selected portion of the product of the mine was caustic calcined for plastic purposes. MAGNESITE IN CALIFORNIA. 71 Tlie Sami)soii iiiagnesite mine is owned by R. H. Moore, Hugo Fischl and Alex. Morrison, Sharon Bldg., San Francisco. It is under lease to C. S. Maltby, Humboldt Bank Bldg., San Francisco. Bibliography: Cal. State Min. Bur., Reports XV, pp. 643-645; XVIIT, pp. 218-219; XIX. p. 26; XX p. 28. U. S. Geol. Surv., Bull. 355, p. 38; Bull. 540. pp. 503-50!); Bull. 603, p. 208; Min. Res. of U. S., 1911, Pt. II, p. 1120. Standard Group (includes Jerome and other claims). This group of 8 claims was located in 1917, by Hugo Fischl, HoUister, in Sees. 35 and 36, T. 17 S., R. 11 E., M. "D. M., southeast of the Sampson Group. The outcrop is stated to be traceable for 3500 feet in length. Magnesite is found over a width of 50'-60', though it is not all ore. In October of that year, four men were working on development. Samples of the magnesite submitted were of good quality. There is also a large body of hydro-ma gnesite. The group is 4 miles from Idria by a wagon road formerly used by the New Idria Quicksilver Company for getting out timber. In 1924, the claims were taken over by H. A. Palmer et al, of Holly- wood, and the Superior Magnesite Company organized. A road has been built from Hernandez to the group, making it 35 miles to Coalinga and 38 miles to Kings City. Machinery has been hauled in and is now (July, 1925) being installed. 72 CALIFORNIA STATE MINING BUREAU, SAN BERNARDINO COUNTY. Afton Magnesite Deposit. A deposit of magiiesite of unusual size has been discovered about one and a half miles east of Afton station on the Los Angeles and Salt Lake Railroad. It lies 1900 PT.ATE VI. feet by actual survey southeasterly of the railroad, thus being very accessible to shipping facilities. The deposit has been covered ])y three lode locations, namely: Cliff Side, Hill Top, and Crown claims. It is owned by the Cliffside Magnesite Company, John M. Nordheim, president, 518 West 41st Place, Los Angeles, 'and W. J. Swan, secretary, San Bernardino. MAONESITE IN CALIFORNIA. 78 Tlie inaunt^site on the Clitt' Side claim (see sketch map) outcrops as a bold white ledge striking easterly over a precipitous ridge which rises abruptly out of the Mojave River bed to an elevation of 500 feet above the river. The magnesite ledge is exposed for about •400 feet from the base to the top of the croppings and it forms a striking landmark visible, for several miles west of the deposit, as I is shown in Photo Xo. 29. Phot" X". :j:i--:\Iagiifsite outcrop un the Cliff ;-ide Claim near Afton, S;in Ber- nardino County. This cropping continuous for about 4 00 feet. Photo by C. A. Waring. i'HuTu No. :i'i Aii< Photo by C. A. Warint?. >p un the Hill Top tUaim. Near the top of the croppings a slide has denuded it, showing a thickness of a couple of hundred feet and dip of 40^ northward towards tlie rivei-. At least 1000 tons of ore are exposed at this place. The magni'sitc underlies a soft, red-colored, decomposed, conglom- t rate material with which it forms a striking coloi' contrast. This conglomerate bed is several hundred feet thick and is superimposed 74 CALIFORNIA STATE MINING BUREAU. by a massive bed of fine-grained gray sandstone, wliose dip is eon- formable to that of the magnesite. Most of the sandstone has been eroded, so that it only outcrops in one place. Underlying the magne- site are decomposed sandstones and dark, slaty shales. The magnesite varies in color from pinkish to grayish white and pure white. Near the hanging M^all, it is deposited in nodular form, the individual nodules vary from egg size to boulders of several inches diameter. Nearer the footwall it is more compact and stratified, varying from massive to thinly laminated. Occasional seams of silica occur interbedded with shaly magnesite in the foot- wall. I Photo No. 31 — Magnesite exposure on the Qviaker Group southeast of Cima, San Bernardino County. Photo by Geo. W. Elder. Analyses of samples taken from three places along the outcrop spaced 20 feet apart are given by W. J. Swan, as follows : No. 1 No. 2 No. 3 Per cent Per cent Per cent Silica (SiO-.) 10.14 10.12 10.10 Alumina (AI2O3) -- 4.40 3.69 1.73 Iron (FegOa) 0.7S 0.67 1.41 Lime (CaO) 1.74 3.36 3.10 Magnesia (MgO) 36.48 35.62 38.19 Alkalies 0.S6 O.SS Carbon Dioxide (OO2) 45.68 45.80 40.65 Analysts: Nos. 1 and 2— Smith, Emery & Co.; No. 3— Sill and Sill. MAGXESITE IX CALIFORNIA. 75 On the Hill Top Claim (see Photo No. 30), erosion of the overlying sediments has nneovered a large body on the hillside, which at the surface is rather soft, due to exposure. A good idea of the size of this body may be obtained by comparing it with the discovery monument slioAvn in the photograph, directly above it. Very little work has ])een done at the claims other than some stripping of the overburden on the Cliff Side claim. AV. J. Swan and associates have erected an aerial tramway from the base of the cropping on the Cliff Side claim to the railroad. Tt is proposed to build a calcining plant at San Bernardino to treat the material. Judging from the extent of the croppings, the apparent uniformity of the magnesite. and its accessibility to a railroad, the deposit should become an important producer. Bibliography. Report XYII. pp. 353^-354. Qual^er Group. Geo. W. Elder, 799 Oak St.. San Francisco, reports having filed relocations (1923) on a group of 4 claims covering a deposit of magnesite' 12 miles southeast of Cima, in the Providence ]^Iountains. It is stated that a shipment of 200 tons was made from this deposit to a plant at San Diego, before the Avar. The magnesite is on the contact between serpentine (footwall) and limestone (hanging wall). 76 CALIFORNIA STATE MINING BUREAU. SAN DIEGO COUNTY. No magnesite deposits have as yet l)een found in San Diego County but there was a calcining plant in operation a few miles south of the city of San Diego for several years, treating magnesite that is mined at Santa IMargarita Island off the coast of Lower California. International Magnesite Company. Dr. R. Schiffman, president, home office, Chamber of Commerce Bldg., Pasadena, Cal. This plant is situated at Chula Vista, seven miles south of San Diego. It has a daily capacity of forty tons, the flow-sheet being as follows : The coarse magnesite was broken down to about 1" size by a No. -S gyra- tory crusher, and then transported by a belt conveyor to two sets of rolls where it was still further reduced. It was then fed directly to a 5' X 40' oil-burning rotary ealciner. From the calciner the product was elevated to a 40' cooling tower. It was then about ^" size, and running dO'/o MgO. Most of the calcined magnesite was shipped in bulk Avithout grinding, to steel manufacturers in the east ; about 10^ of the output ])eing used for plastic purposes. For this use it Photo No. 32 — I'laiii ui inieruaiiuHitl Magii'-siU Cen confiicting factions in the company. The company, organized in 1912, owns the magnesite mine on Red Mountain formerly owned by the American Magnesite Company. The property consists of ten claims, four of which are patented, and has been a producer since 1905. The magnesite outcrops in bold white ledges on the southern and western slopes of the mountain, several hundred feet above the floor of the valley. The following 6—39802 82 CAIJFORNIA STATE MINING BUREATT. • 3 C c in 2^ i ri.ATE VIII MAGNESITE IN CAIJFORNIA. 83 tlesei'iptioii of the i^-eolo^^v is (iiiotcd from the report of (Jale,' wlio made an examination of the deposits in September. 1!)12: "The general area containing the masnesite outcrops is occupied by serpentine without evidence of much variation in character or of incluslveness of other rocks. The serpentine is bordered on the west by sedimentary sandstones and shales which form a distinctlv different topography. Tlie otlier limits of the mass of serpentine rock have not been defined. The original country rock from which the serpentine is derived is described by Hess= as Iherzolite and peridotite, and is composed essentially of the minerals olivene, diopside, and an orthorhombic pyroxene. The mineral serpentine is a natural alteration product from such rocks. The original country rocks are composed princii^ally of silicates of magnesia (silica 40 + %: m;ignesia 25 to i0'7'( ; alumina and iron variable, usually 59f or more; and a small percentage of alkalies). It is natural to assume the magnesite might be derived by tlie decomposition or alteration of these silicates being deposited as veins along fissure zones, or by replacing tlie country rock. As a whole, however, the serpentine of this area does not show the excessive amount of shearing to be seen at any of tlie otlier magnesite localities. "Throughout the dark-red soil that covers the area of serpentine country rock, especially in the zone that contains the magnesite veins, silica is present in various 'luiTo Nil. :i:! — ( ip.'u lilt of Wcst»Tii Magnesite Development Company (in 1915). Note lack of outcrop of this large lx)dy of magnesite. Ground surface sliowing in upper right half of picture. forms. It occurs, in part, as a white rosiny opal, scattered fragments of which are strewn about on the surface, or it may be observed as chalcedonic veins or coatings in the joints of the country rocks. The silica associated with the purer mass of magnesite in the larger pit was in the form of a pale-greenish granular iiuartz. "The magnesite veins are very irregularly distributed and appear to trend in all directions. The larger developed masses are of most unusual size, and even the great bodies that have been removed by' mining have been taken out in large "l)en caves or chambers, so as to give little evidence of the real extent or size of tlie deposits underground, beyond that which has been taken out." 'Gale H. S., Magnesite deposits in California and Nevada: U. S. Geol. Surv., Bull. 540, pp. 4;iS-501, 1914. = Hess, P. L., Magnesite deposits of California: U. S. Geol. Surv., Bull. 355, p. 34. 1908. MAGNESITE IN CAI.IFORNIA. 83 (U'serii)tion of tlie j,H'ol()fi:y is ((uolcd fi-oin the report of dale,' who iiuule an examination of the (U'posits in Septenil)er. 11)12: "The general area containing the masnesite outcrops is occupied by serpentine without evidence of much variation in character or of inclusiveness of other rocks. Tlie serpentine is bordered on tlie west by sedimentary sandstones and shales which form a distinctly different tojiography. The other limits of the mass of serpentme rock have not been defined. Tlie original country rock from which tlie serpentine is derived is described by Hess= as Iherzolite and peridotite, and is composed essentially of the minerals olivene, diopside, and an orthorhombic pyroxene. The mineral serpentine is a natural alteration product from such rocks. Tlie original country rocks are composed principally of silicates of magnesia (silica 40 + %; magnesia 25 to 40'X ; alumina and iron variable, usually 5% or more; and a small percentage of alkalies). It is natural to assume the magnesite might be derived by the decomposition or alteration of these silicates being deposited as veins along fissure zones, or by replacing the country rock. As a whole, however, the serpentine of this area does not show the excessive amount of shearing to be seen at any of the otlier magnesite localities. "Throughout the dark-red soil that covers the area of serpentine country rock, especially in the zone that contains the magnesite veins, silica is present in various HoTo No. .'!:! — Open cut of Western Magnesite Development Company (in 1915). Note lack of outcrop of this large Ixidy of magnesite. Ground surface sliowing in upper right half of picture. forms. It occurs, in part, as a white rosiny opal, scattered fragments of which are strewn about on the surface, or it may be observed as chalcedonic veins or coatings in the joints of the country rocks. The silica associated with the purer mass of magnesite in the larger pit was in the form of a pale-greenish granular quartz. "The magnesite veins are very irregularly distributed and appear to trend in all directions. The larger ileveloped masses are of most unusual size, and even the great bodies that liave been removed by' mining have been taken out in large open caves or chambers, so as to give little evidence of the real extent or size of the deposits underground, beyond that which has been taken out." ' Gale H. S., Magnesite deposits in California and Nevada : U. S. Geol. Surv., Bull. 540, pp. 49 8-501, 1914. = Hess, F. L., Magnesite deposits of California : U. S. Geol. Surv., Bull. 355, p. ."54, 1908. 84 CALIFORNIA STATE MINING BUREAU. Plate IX, WHITE DIAMOND WORKINGS MALTBY MAGNESITE MINES N? I LIVERMORE. CALIFORNIA o 5 oo-r-es^ of c ! MAGNESITE IN CALIFORNIA. 85 The properties of the Western IMagnesite Development Company are located mainly in T. 6 S., R. 5 E., M. D. M., along the summit of Red ]\Ionntain ridge which forms the boundary line between Santa Clara County and Stanislaus County, to the east. This group has been operated under lease by C. S. ]\laltby, Humboldt Bank Bldg., San Francisco, since 1919. Many improvements have been made in the plant equipment, and new orebodies have been developed. The earlier underground operations were due east from the furnaces, and some ore is still ])eing drawn from that portion of the property. Ivater developments have been towards the north and northwest from the older Avorkings. While none of the north-end stopes have as yet reached the size of some of the older south-end orebodies (there was one. ;^00' long x 50' wide x 300' high ; and another 200' long x 150' high X 30' wide), some are over 20' wide in places. The ore is of the same, white, high-grade character. The accompanying maps of the claims and the mine workings are are here reproduced through the courtesy oi; Mr. Maltby and his mine superintendent, Mr. Roy II. Clarke. The magnesite is in gen- eral high grade, though towards the border of the larger bodies it becomes mixed with the soft serpentine country rock, having a yellowish color, so that there is no well-defined boundary. Ore from the north end is trammed around the hill (see photo) to the loading bunkers of the main aerial tram (of which there were two). The larger and heavier of the tv*'o tramways to the main south workings is 3000 feet long Avith a drop of 550 feet from ore bins to furnaces. When visited in November, 1923, preparations were being made for the installation of a third aerial tramway, at the north end, in order to eliminate the long haul around the hill. A total of 150-200 tons of ore per day was being delivered to the furnaces, of Avhich 40 tons was being mined at the south end, 30 tons from the extreme north end, and the balance from the main north workings. A new 4-inch pipe line was being laid direct to the north end to serve those workings with compressed air, in place of the line from the south end around the hill. Pressure is maintained at TOO pounds at the compressors (two 50 h. p. Chicago Pneumatic, direct-connected to oil engines; also a Doak compressor as extra stand-by) and at least 90 pounds at the mine. There are four upright kilns which l)urn the lump ore, and a Scott fine-ore fjuicksilver furnace which handles the fines. ^ The burners nsed on the upright kilns have 2, 3 and 4 tips, in order to spread the Hame; I>ut, single-tip burners are used in the Scott furnace. The ore as it comes from the mine is dumped on grizzlies set with a l;',-inch oi)ening; and the through material passed over a ^-inch screen. The plus i[-inch material goes to the Scott, and the minus ^-inch to the waste dump as it contains mostly impurities. There is a Thwing electric pyrometer on the Scott furnace, by which the temperature is maintained at 2100° F. The calcines are drawn each hour, and an output of 20-24 tons per day obtained. The upright k'ilns are drawn every 2 hours, and their output totals 50 tons daily for the four. The ])urned lump ore is carried by a belt conveyor to • Since the above was written, we are informed that a rotary kiln has been added for calcining the fines. MAGNESITE IN CALIFORNIA. 85 The properties of the Western Magnesite Development Company are located mainly in T. 6 S., R. 5 E., M. D. M., alonp: the summit of Red ]\Ionntain ridge which forms the boundary line between Santa Clara County and Stanislaus County, to the east. This group has been operated under lease by C. S. IMaltby, Humboldt Bank Bldg., San Francisco, since 1019. Many improvements have been made in the plant equi])ment, and new orebodies have been developed. The eaj'lier undergi-oiind operations were due east from the furnaces, and some ore is still being drawn from that portion of the property. Later developments have been towards the north and northwest from the older workings. While none of the north-end stopes have as yet reached the size of some of the older south-end orebodies (there was one, 300' long x 50' wide x 300' high ; and another 200' long x 150' high X 30' wide), some are over 20' wide in places. The ore is of the same, white, high-grade character. The accompanying maps of the claims and the mine workings are ai-e hei-e reproduced through the courtesy of ]Mr. Maltby and his mine superintendent, Mr. Roy II. Clarke. The magnesite is in gen- ct-al high grade, though towards the border of the larger bodies it becomes mixed with the soft serpentine country rock, having a yellowish color, so that there is no well-defined boundary. Ore from the north end is trammed around the hill (see photo) to the loading bunkers of the main aerial tram (of which there were two). The larger and heavier of the two tramways to the main south workings is 8000 feet long with a drop of 550 feet from ore bins to furnaces. When visited in November, 1923. preparations were being made for the installation of a third aerial tramway, at the north end, in order to eliminate the long haul around the hill. A total of 150-200 tons of ore per day was being delivered to the furnaces, of which 40 tons was being mined at the south end, 30 tons from the extreme north end, and the balance from the main north Avorkings. A new 4-inch pipe line was being laid direct to the north end to serve those Avorkings with compressed air, in place of the line from the south end around the hill. Pressure is maintained at 100 pounds at the compressors (two 50 h. p. Chicago Pneumatic, direct-connected to oil engines; also a Doak compressor as extra stand-by) and at least 90 pounds at the mine. There are four upright kilns which burn the lump ore, and a Scott fine-ore quicksilver furnace which handles the fines.^ The burners used on the upright kilns have 2. 3 and 4 tips, in order to spread the tiame; but, single-tip burners are used in the Scott furnace. The ore as it comes from the mine is dumped on grizzlies set with a Ij-inch opening; and the through material passed over a ff-inch screen. The plus iJ-inch material goes to the Scott, and the minus ^-inch to the waste dump as it contains mostly impurities. There is a Thwing electric pyroineter on the Scott furnace, by which the temperature is maintained at 2100° F. The calcines are drawn each hour, and an output of 20-24 tons per day obtained. The upright kilns ai-e drawn (!very 2 hours, and their output totals 50 tons daily for the four. The Inii-ned lump ore is carried by a belt conveyor to ■ Since the above was written, wo are informed that a rotary kiln has been added for calcining the fines. 86 CALIFORNIA STATE MINING BUREAU. MAGNESITE IN CALIFORNIA. 87 a troinnu4 with 1-inch apertures. The waste and oflt'-eolored matyne- site are picked off the belt. The iinbiirned cores after passing out of the trommel are hauled back to the main ore bin and reburned in the kilns. Steam for atomizing the fuel-oil is provided by two boilers, of 100 h. p. and 65 h. p., respectively. There were 14 motor trucks in service, hauling the calcined magnesite to the railroad at Tiivermore. On the return trip they bring out fuel-oil in drums. BihJio(jraphy: Cal. State Min. Bur., Reports XI. p. 374; XII, p. 328'; XIII. p. 505; XVII, pp. 189-192; XX. pp. 29-30; Bull. 38, pp. 330-331. U. S. Geol. Surv., Bull. 355, pp. 33-37 ; Bull. 540, pp. 498-501. Eng. and Min. Jour.-Fress. Vol. 120. pp. 178-180, Aug. 1. 1925. Photo No. 36 — Ti-amming ore from north end of White Diamond workings, at MaUby No. 1 Mine (Western Magnesite Development Co.) on Red Mountain. Winship Properties. K. 1). Winshii) Estate. 350 Post St.. Shu Fran- cisco, owner. Magnes^ite occurs on Sees. 1 and 11, T. 6 S., R. 4 E., and on the SW-j of Sec. 7, T. 6 S., R. 5 E., M. D. ]M. The two latter were leased to the John D. Hoif Asbestos Company with offices at 333 Monadnock Bldg.. San Francisco. The principal development work. so far. has been done on Sec. 11 from which several carloads of crude magnesite were shipped in 1916, via Livermore. 88 CALIFORNIA STATE MINING BUREAU. ^4. Photo No. 37- — Vertical kiln of the Western Magnesite Development Company. Photo No. ?,S — gcott. fine-ore, quieksilver furnace (at right), rebuilt and in use for calcining magnesite fines at Western Magnesite Development Company (Maltby No. 1) property, Santa Clara County. Storage bunkers with elevator for calcined fines in center. Four vertical-stack kilns at left, for burning lump ore. Photo by C. S. Maltby. MAGNESITE IN CALIFORNIA. 89 SONOMA COUNTY. There are numerous deposits of uiagnesite in Sonoma County, some of which are in the district around Cloverdale, and another group is situated northwest of Guerneville in a belt of serpentine which strikes northwestward through T. 8 N., R. 10 W., and T. 9 N., R. 11 W.. ]\I. D. M. The latter region is rather inaccessible, being characterized by densely vvooded and brush-covered ridges separated by narrow eafions. It was not until 1913 that attempts were made to exploit the deposits. The more important of these are controlled by the Sonoma INIagnesite Company and the Western Carbonic Acid Gas Company (now Harker Estate), the former having shipped during 1915 and 1916. several thousand tons to New York via the Panama Canal. The magnesite deposits northwest of Guerneville shoAV some of the most extensive surface exposures in the state, and it is due mainly to their inaeeessilnlity that they are idle. The roads to both Cazadero and Guerneville, the nearest railroad stations, are almost impossible to haul over due to the heavy grades. The construction of a 2'1-inch gauge railroad up East Austin Creek to within three miles of their deposit, by the Sonoma Magnesite Company, did away with the haul to Cazadero, but as the magnesite has to be transshipped to the narrow gauge at Magnesite station, and then in turn to the ])road gauge seven miles beyond at Duncan Mills, the freight rate by this route is high. With better transportation facilities, this district should become an important producer. Bihliographij: Cal. State Min. Bur., Reports XIV, pp. 324-333; XVil, p. 249; Bull. 38, pp. 331-333. U. S. Geol. Surv., Bull. 355, pp. 22-28 ; Bull. 540, pp. 480-498. Albertz Ranch Deposits. A vein of magnesite has been mined on this property two miles southwest of Cloverdale, by a trench or cut driven along it for 80 feet. The inner end of the cut is about 30 feet deep, and shows in the face 6" to 1 ft. of chalky white magne- site. The vein which dips vertically in places, is 3 feet thick, aver- aging about 2 feet. Parts of it are full of serpentine breccia. One carload has been shipped and there were about 40 tons' in stock, when visited. Fifty feet from this trench is the top of another vein, probably 15" to 24" thick, undeveloped. The developed vein pinches out and has not been traced on the surface. Pi'obably a few hundred tons may be developed on the second vein. Ferdinand Albertz, Cloverdale, owner. Battenburg Refractory Magnesite Mine (formerly known as the Creon or Rolling deposit). It is situated in See. 32] T. 12 X., R. 10 AV., M. D. M., three miles by road east of Preston station, near the top of a ridge at an elevation of 1500 feet. The wagon road to Preston has a heavy grade, but it is all down hill, and the magne- site was hauled out by teams at $1.50 per ton. The deposit occurs in the form of disconnected veins oi' narrow lenses in the serpentine, which trend north and south, and dip almost vertically. These vai-y in thiekness from a few inches to several feet, and up to 50 feet in length. The serpentine is so faulted that there is no continuity to the veins, and consequently 90 CALIFORNIA STATE MINING BUREAU. their extent is very uncertain. Development work consists of two tunnels, the lower 50 feet vertically below the upper. Five lenses have thus far been developed in the upper tunnel which is over 300 feet long, and three in the lower which is over 400 feet in length. Several of the lenses or orebodies have been exhausted, having been stoped between the two levels. A few small croppings north of the mine were being developed by open cuts, when operations ceased. Quoting from Bess's report: ^ "The magnesite in the worked deposit is but little discolored, and portions are pure white, but all through it is scattered some serpentine only partially altered to magnesite. The mass has been much crushed and the pieces have been recemented by crystalline magnesite of a slightly greenish-yellow color, which forms a layer about one thirty-second of an inch thick around the fragments. In places colorless, fragile, platy crystals coat the cavities." Photo No. 39 — Kiln of the Refractory Magnesite Mine, east of Preston, Sonoma County. The dead-burned product from this mine is brown in color, very much resembling the Austrian 'spaeder,' so much desired as a refrac- tory. Analyses show an average of around 6% FeoO;^, with a low silica and no lime content. The raw material appears to be an isomorphous mixture of the carbonates of magnesium and ferrous iron, the pale-green color on thin fracture-edges being due to the iron. The entire output was dead-burned at the mine, and shipped to a fire-brick manufacturing plant at Stockton, the resulting magne- sia bricks being utilized by metallurgical plants in California and Utah. The magnesite is calcined in a 30-ton capacity stack kiln, using crude-oil fuel. A 20 h. p. gas engine and compressor supplied the necessary air for the hammer drills used in the mine. An average 'Hess, F. L., Magnesite deposits of California: U. S. Geol. Surv., Bull. 355, pp. 22-23, 1908. MAGNESITE IN CALIFORNIA. 91 of ten men were employed, the production being four to five tons of calcined rock daily. Tlie mine, opened about 1907. was worked l)y the present owner, the Refractory ^Maunesite Company, F. R. Turton, president (since deceased), from 1914 to 1921. A total of several thousand tons has been produced. Bibliography: Cal. State Min. Bur.. Reports XIV, pp. 325-826; XVII, p. 249; Bull. 38, pp. 331-332. U. S. Geol. Surv., Bull. 355, pp. 22-24. Burgans Ranch Deposit. Numerous small stringers or veinlets of magnesite occur in the serpentine on this ranch, Avhich is about a mile north of the Battenburg mine, and on the same ridge. About 250 feet beloAv the summit of the ridge, an open cut was made on several veinlets. It is in probably 15 feet, showing a stockwork of veinlets across a 6-foot face; 260 feet below the cut a funnel was ■ driven about 20 feet, but failed to disclose any vein. Some large lioulders of almost pure-white magnesite are found on the ranch, but no deposit of any commercial importance has been developed, ("has. H. Burgans, Cloverdale, owner. Madeira Deposit (also known as Healdsburg Marble Company). It is in the southwest corner of Sec. 31, T. 9 X., R. 10 W., M. D. M., 5^ miles north from Guerneville; elevation 1700 feet, (bar.). There is a series of magnesite veins from a few inches to ten feet wide, occurring in serpentine over a width of about 1400 ft. They strike west of north and dip west at about 70°. The larger veins are of very uood (luality. There is a considerable tonnage in sight at the surface which can be cheaply quarried, but except for a couple of short tunnels, there has been no development work underground. At its west end, the veins are narrow and banded with a green dolomitic material, chalcedony and quartz, forming a variety of 'verde antique marble.' It Avas for this that the deposit was origin- ally located (1894) with the intention of putting it on the market as an ornamental building stone. The property is idle and has no transportation outlet as yet, but it is only a half mile from the claim of the Western Carbonic Acid Cas Company, which has a wagon road to Guerneville. The claims are patented. Estate of George Madeira, owner. Bibliography. Cal. State Min. Bur., Reports, XIII, p. 640; XIV, p. 325; Bull. 37. p. 112; Bull. 38, pp. 114, 333, 369. IT. S. Geol. Surv.. Bull. 355, pp. 25. 26 ; Bull. 540, p. 497. y W Meeker Ranch Deposit. It is in Sees. 2 and 3, T. 8 N., R. 11 ^., M. D. M., seven miles by road north of Guerneville. The outcrop of magnesite is close to the top of a knob, between Gilliam and Rock creeks, known as Morrison Ridge, and only one mile S. 20 W. from the Western Carbonic Acid Gas Co.'s mine, described below. The magnesite is conspicuously exposed for 400 feet continuously in a ledge 10' to 40' wide, and rising 15' to 20' above the soil. This large outcrop contains two good veins 4V and 1^' thick, respectively. The remainder of the ledge runs northwest and is vertical. It has l>een prospected by a small cut in the lower side. A road has been 92 CALIFORNIA STATE MINING BUREAU. built one-half mile, to reach it, and one carload was shipped out during the summer of 1917. Down the hill towards Gilliam Creek, there are several small exposures. It is estimated that probably 5000 tons of ore could be secured from the surface without dead work. The only disadvantage is the haul to the railroad, two miles of which is up hill. The property was taken over in 1916 by the Guerneville Farms Company, Jacobs, Malcome and Burt, managers, 101 Washington St., San Francisco, who did some development work, but nothing has been done recently. Bibliography : Cal. State Min. Bur., Report XIV, p. 327 ; Bull. 38, p. 333. U. S. Geol.. Surv., Bull. 355, p. 28. Melville Ranch. Magnesite has been mined spasmodically for several years on this property, formerly the Eckert, and later the Yordi ranch. It is situated two miles southeast of Cloverdale on a steep hillside just above the valley floor. The ore consists of boulders of magnesite in soft serpentine. The boulders are in fairly close contact, forming an orebody which averages 3 feet in thickness, but varies up to 8 feet. Its course is N. 30° E. The ore is white and massive with some 'pop corn' structure. It is said to carry about 3% silica and no lime. Development consists of an open cut 75' long, and 18' to 20' wide and deep, under which the mining has been done. A tunnel driven N. 50° E. cut the 'boulder vein' at 150'. 30' below the bottom of the open cut ; it then followed the vein for 30 feet. The ore was taken down by stoping above the drift, being mined by pick and shovel, as drilling was unnecessary. W. B. Smith and L. C. Stephens of Cloverdale, lessees during 1917, shipped sev- eral hundred tons of crude ore. The property has been idle since 1918 or 1919. Bibliography : Report XIV, p. 333 ; Bull. 38, p. 333. U. S. Geol. Surv., Bull. 355, p. 23 ; Bull. 540, p. 498. Snyder Ranch. There is said to be an undeveloped deposit of magnesite on the George Snyder ranch on Piney Creek, about 12 miles southwest of Healdsburg. Bibliography: Report XVII, p. 249. The Sonoma Magnesite Company (also referred to as the Red Slide Deposits) owns a group of thirty claims on East Austin Creek in Sees. 6, 7, 8, 17 and 20, T. 9 N., R. 11 W., M. D. M., 6 miles north of Cazadero. During 1914, a 24" gauge railroad was laid 8 miles on a road grade from a spur of the narrow-gauge railroad above AVatson station to within 3 miles of the camp. The ore was hauled to the railroad by motor trucks. The company also erected a calcining plant (see Photo No. 42), with a capacity of 30 tons per 24 hours, at the property. In 1917 a second furnace was added. The deposits were worked for over two years and shipments were made via the Panama Canal to New York. Operations ceased temporarily in the fall of 1916, on account of financial trou])les. This was in part due to the excessive transportation costs, its product having to be handled three times after leaving the property — (1) the 3 miles haul to the 24" tram, (2) the 8-mile haul to the narrow gauge at Magnesia sta- MAGNESITE IN CALIFORNIA. 93 tion, (3) transshipping 7 miles l)eyond, at Duncan Mills to the broad uauge Northwestern racifie Railroad — and to the irregularity and uncertainty of the deposits developed. There are three groups of magnesite outcrops with a northwest trend in a large belt of serpentine. The principal work has been confined to the lower group in Sec. 20. Development work here consists of two tunnels and a large open cut. The lower tunnel was started as a drift on the outcrop of a 9-ft. vein, but after 50 ft. turning to the northeast and running as a crosscut for almost 200 feet, where a small step-faulted vein of magnesite was struck. The upper tunnel, 50 feet above the lower, was also started on a large outcrop, but driven as a crosscut. It cut veins showing Avidths of 12', 5', 15", 18", and 8", as well as smaller ones. Some drifting Photo No. 40 — Vein of magne.sile, as exposed in an open cut on the Alfred claim of the Sonoma. Magnesite Company. Dips into the hill (easterly) at a flat angle. has been done on the larger veins, but most of the work was done at the quarry or open cut below, where it is said a large tonnage was taken out. At the upper claims, H miles northAvest of the lower workings, a tunnel was driven N. 48' p]., 230 feet ])elow some large croppings of magnesite which form prominent ledges on the steep slopes above. Gale in his report ^ on this property states : "The exposure higher on the slope consists of a large projecting ledge of white magnesite, wliich makes a conspicuous feature in the thickly-forested and brush- covered hillside. The thickness and attitude of the ledge are difficult to di-termine from the present exposure, as an apparent vein-handed structure dipping 40° NE. is most evident in the ledge, and yet the attitude of the extension of this massive ledge to the soutlieast, as viewed from a distance, is that of a rather steep dip towards the creek, or southwest. For this reason the section measured on the ' Gale, H. S., Magnesite deposits in California and Nevada : U. S. Geol. Surv.. Bull. r)40, p. 493, 1914. 94 rAl.IFORNIA STATE MINING BUREAU. outcrop, giving a tliickness of :](» to 35 feet across the l)anded structure, very likely does not represent the true cross section of tlie vein. Magnesite constitutes a very large part of the mass, however, as is indicated ))y surface exposures and further underground exploration of the deposit will be necessary before its limits can be more positively defined. The extent of tliis deposit in either direction is also a matter of mucli uncertainty. A ledge similar to the magnesite outcrop was observed to the northwest, and evidently the ledge extends about S. 30° E. from the outcrop that was examined above the tunnel. According to report the ledge has been traced 300 feet to the north and 400 feet to the south, but the deposit is supposed to be thickest near the center. "The magnesite of both the upper and lower claims appear to be of similar character. The outcrop consists of rough weather-stained rock. * * * Where the rock is liroken off, the magnesite shows a chalky white surface, in patches having the typical white china-like fracture, but the mass is irregularly broken or jointed and filled with seams and cavities lined with silica." Later developments (see Photo No. 40) by open cut on the vein show that it does dip into the hill (easterly), as suggested by Gale, above. Its thickness is at least 20 feet at that point. Photo No. 41 — Ore chute at upper deposit of Sonoma Magnesite Company. MAGNESITE IN CAUFORNIA. 95 The followino- analyses of samples from the ui)per and lower claims are taken from an earlier - report. Sample From SiO, AljOs FesO, CaO MgO CO, MgCO. Vndeter- mined ' Cecilia (upper tunnel, lower o!aim.«) ' Ceeilia (lower claims J _ - • Alfred (upper claims) . . ' Alfred (upper claims) , . ^ Vera Xo. 2 (Calcined upper claims) ' Alfred (Calcined upper 7.67 3.66 '2.50 2.50 0.74 6.66 7.85 0.26 0.75 0.29 0.44 .55 9 0.04 0.20 '2.30 Xone 0.52 43.42 44.90 46.0 94.21 82.60 87.31 48.08 49.20 «49.3 93.92 0.24 0.85 /0.36\ »\0.37/ 5.05 10.22 0.21 1 4.63 = Vera (Calcined upper ' Analysis by .\. J. Peters, (U. S. Geological Survey). -■ Anaiysis by W. C. Wheeler (L'. S. Geological Survey). ' Anaiysis by StaufFer Chemical Co., San Francisco. • Anaiysis by Selby Smelting and Lead Company. 5 Anaiysis by Booth, Garrett and Blair, Philadelphia, Pa. ' Silicates. ' Calcium carbonates. ' Calculated. ' Moisture. PHdTO No. 42 — Rotary kiln of Sonoma Magncsite Co.. at 'MagiU'siu monia t'ounty. The .sueeessful exploitation of this i)roperty depends on several factors, mainly reduced transportation costs and skillful manaurement. Considerably more development Avork should he undertaken upon the larger veins to determine whether they are pei-sistent or merely erratic deposits. Early in 1924. the property was taken over by = Bradley, W. "W., Mines and mineral re.sources of Colusa, et al, counties: chap- ters of State Mineralosist's report, biennial i>eriod. 1913-1914, Cal. State Min. Bur., p. 159; also in Report XIV, p. 331, 1916. 96 CALIFORNIA STATE MINING BUREAU. Spreckels Bros, of San Diego, and some development work carried on, hut there has been no production since 1920. Bibliography: Cal. State Min. Bur., Report XIV, pp. 327-331; Bull. 38, p. 333; Bull. 66. pp. 58, 59; Bull. 71, pp. 48, 49; Bull. 74, pp. 68. 69 : Bull. 83, p. 69. U. S. Geol. Surv., Bull. 355, p. 26 ; Bull. 540, pp. 490-495. Western Carbonic Acid Gas Company, Chas. S. Harker Estate, owner; c/o E. W. Harker. Porterville. Cal. The company owns a Photo No 43 — Calcining furnace of AVestern Carbonic Acid Gas Company, at Guerneville, Sonoma County. group of claims at the head of Gilliam Creek, in Sec. 6, T. 8 N.. R. 10 W., M. D. M., 7 miles north of Guerneville. A wagon road has been built to the claims, but very little ore has been shipped out. The magnesite occurs in the form of veins in serpentine and detached blocks that vary up to 100 tons in size. At the end of the road there is a cropping 30 feet high on the loAver side, 8' to 12' thick, and 40 feet long. All of the ore shipped to date was furnished by breaking up an 80-ton boulder. Near the loading platform a tunnel driven 38 feet to the northeast cut a 3-foot ledge dipping 30° E. The MAGNESITE IN CAIJFORNIA. 97 vein is faulted and offset nearly its full width. Further up the hill, tliere are several exi)osures of niagnesite, l)ut they have not been develoi)ed. There are ])ro])ably 75 tons on the stock pile, and there could easily he i-ecovercd from the boulders and the larjjfe ledge, .15()() tons or more. A stack kiln 5 feet inside diameter and 29 feet high was built in October, 1917, at Guerneville to burn this ore. (See Photo No. -43.) Work at the mine had been resumed by the company that summer, but only a few men were employed. A few carloads of ore was hauled down to the plant, but work ceased, following the decease of Mr. Harker. The plant at Guerneville was designed to produce the re-precipi- tated light carlionate, or 'magnesia alba,' as well as the ordinary magnesia. Biblio(jraphij: Cal. State Min. Bur., Report XIV, p. 332. U. S Geo'l. Surv.. Bull. 355, p. 2-4; Bull. 540, pp. 495-497. 7—39802 98 CALIFORNIA STATE MINIX(i BTREAU. STANISLAUS COUNTY. iMagnesito deposits are now being developed on the east slope of Red Mountain, whose suniniit marks the division between Stanislaus on the east and Santa Clara County on the west, and it is prol)al)lc that other deposits occur in the brush-covered and little-traversed hills to the south. The Red Mountain deposits of the east slope have been located for many years, but it was not until 1936 that an>' attempt was made to develop them. This was due to the comple- tion of the Patterson and Western Railroad to the foot of Red JMoun- tain which made them easily accessible. Though that railroad has now been discontinued and the rails taken up, the road-grade is being utilized for auto-truck hauling. Another series of deposits has also been opened up on Quinto Creek in the southwestern corner of the county near the JNIerced County line west of Ingomar. Bald Eag-le Claim. This claim, in Sec. 82, T. 8 S., R. 7 E., M. D. M., was located by A. D. Davenport, of Gustine, and was operated under lease in 1917, by the Gustine ^lagnesite Comj^any, as described below. Geo. V. Borchsenius, of Patterson, reports that he has a group of claims on a magnesite deposit in the Arroyo del Puerto district neai- the Red Mountain mine, west of Patterson. California Magnesite Co. (Red Mountain Mine)/ G. A. Scott, president ; M. W. Kirk, secretary ; home oftice. Fifth and Parker Streets (Blanding Iron Works), Berkeley, J. Frame, superintendent, Patterson, California. This mine is situated on the Stanislaus County side of Red Mountain in Sec. 20, T. 6 S., R. 5 E'.. at an elevation of 2500'. There is no timber but considerable brush. A large spring supplies all the water needed. The property consists of four claims and a mill site, a total of about S5 acres. The deposit was discovered in 1915 by James and Plunket. The original company was known as the Red INIountain Magnesite Co. Later it was called the W-K Co. In January, 1922, it was reorganized as the California Magnesite Company. The deposit consists of parallel lenses of high-grade magnesite in serpentine country rock, of which Red ]\Iountain is composed. Operations have been by glory hole and stoping from the main tunnel level. Two lenses 18' and 25' wide, respectively, at the tunnel level have been stoped from there to the surface. The main tunnel, which is 1300 feet in total length, has apparently cut the top of two other lenses. The orebodies strike N. 20 W. and dip about 85 into the mountain. The total production since the mine was opened up has been approximately 50.000 tons. This was calcined in part at the mine and also at the calcining plant of the ]\lineral I'roducts Co. in Patterson, which Avas taken under lease. The calcining equip- ment at the mine consists of a shaft fui-nace of 15-tons daily capacity and a small rotary furnace used mainly for burning tines. Crude oil is used for fuel. ISUne equipment consists of two 70-h. p. boilers, a 7-drill Ingersoll-Rand compressor, steam hoist and pumps for handling the water supply, and fuel oil. There is also a 25-h. p. gas 'From manuscript of C. McK. Laiziiie, in ':Miiiing: in California.' .A.pril, lOl'i. Report XXI of State Mineralogist. MAGNESITE IN CALIFORNIA. 99 engine and 2-dnll Sullivan compressor, ears, track, etc. The eanip buildings will accommodate about 30 men. Practically all ore above the present adit was taken out and the mine was shut down in September, 1923, pending additional develop- ment. Another adit about 2o(y below the upper one had just been started to cut the orebodies exposed in the upper adit. This adit will have to be driven about 900 feet to reach the ore. Negotiations are now under way looking to the immediate comple- tion of the new adit and resumption of full operations. It is probable that this move will include taking over the calcining plant of the Mineral Products Co. at Patterson, and possibly the moving of the 90-foot rotary kiln with which it is equipped to the mine as it has proved more economical to burn the magnesite at the mine than to transport the crude material. The road bed of the former Patterson and Western R. R. which ran from Patterson to the foot of Red jMountain, makes an excellent graded road for auto-truck hauling to Avithin a short distance of the mine, so that the pi'operty is not difficult of access. G. L. Fenster et al., Patterson, C'al., own a group of five claims in Sec. 22, T. () S., R. 5 E., M. D. M., adjoining the Red iMountain magne- site mine. There are several croppings of massive white magnesite on the claims, the most promising of which is on the Last Chance claim. The ledge here is nine feet thick, and appears to be quite extensive. There has been as yet practically no development work done on this group, h^nce the commercial importance of the deposits is only prospective. Gustine Magnesite Company. In 1917, this company composed mainlv of Oakland men. operated, under lease, the Bald Eagle. Quinto and other claims in Sec. 32, T. 8 S., R. 7 E., M. D. M. They are on Quinto Creek, 16^ miles west of Ingomar, and near the Merced County line. The ground of the Howard Cattle Company adjoins on the south (see Photo No. 44), in fact both properties are located on th(^ same ore-zone, the township line running diagonally across the area shown in the photograph from the lower left corner to the upper right. The top of the ore-loading bunker of the Gustine com- |)any is just visible in the ravine at the left. The company began operations in June, 1917, opened up the ore- body, and continued shipments for several months, closing down early in 1918. The cessation was apparently due, in part to the difficulty of keeping the workings open, and in part to their neai'ing the property line, as there is still a good body of ore showing where stoping was stopped. The magnesite is in the form of irregular segregations in a soft, decomposed serpentine material. They began stoping from the main adit as they drove in; and the nature of the ground made it necessary to tind)er heavily to keep the tunnel open. When visited, in June, li)18. the Avails had closed in at some points so that it would have been difficult to run an ore car through. Some of the ore shipped from this j)rojierty showetl the higiiest l)urity yet recorded foi- magnesite in California, analysis indicating a total of less than 1% of impurities. The General Electric Com- luiiiy. Schenectady, New York, bought some of this magnesite paying 100 CALIFORNIA STATE MINING BUREAU. t 3 MAQNESITE IN CALIFORNIA. 101 as high as $25 per ton, f. o. b., Ingomar, for at least one carload of sorted material. Some was also sold at $17.o0 per ton, Avhieh was about $5 per ton over the then (Jiil.v, 1!)17) quoted price for crude material, f. o. b. rail. They utilized a part of it in the preparation of magnesium metal by electric-furnace reduction, and a part as an insulation powder for certain electrical installations. This property was idle in 1918-1919, but operated in 1920-1921 by the Plastic ^lagnesite Company of San Francisco. The Gustine Company shipped a total of approximately 2000 tons of crude oi-c during their operations. Bibliography: Cal. State Min. Bur., Report XVII, p. 254. The Howard Cattle Company, Sharon Bldg., San Francisco, is the owner of Sec. 5, T. 9 S., R. 7 E., M. D. M., which contains the con- tinuation of the magnesite deposits opened up on the adjoining Sec. 32 by the Gustine ^Magnesite Company, as described in the pre- eeeding paragraphs. They are on Quinto Creek. 16^ miles west from Photo No. 45 — Magnesite loailing-bunkers at Ingomar, for the Gustine Magnesite and Howard Cattle Company mines. Ingonuir, the shipping point on the Southern Pacific Railroad. When visited in June. 1918, this property was being operated by J. S. ^Middleton, lessee, with N. J. Miller as contractor on the mining of the ore. The magnesite occurs in the form of irregular segregations in an area of soft, decomposed serpentine. Some of the magnesite is clean, liard, and white, and part of it is somewhat powdery, though this latter was stated also to be high grade. In places, above the main orebody, disseminated pellets of magnesite were- noted in the ser- pentine. There are some faults, l)ut none of them have apparently caused any consideral)le disi>lacement. The ore has been stoped, in places up to 12 fe(^t wide. The method adopted has been to drive to the ])ack of the orebody, then fill behind as the ore was stoped Dut. This obviated the timbering difficulties experienced by their neighbors. The lessees began shipping on December 1, 1917, hauling the crude magnesite by motoi- trucks to Ingomar fsce l^lioto No. 45), thenc*- 102 CALIFORNIA STATE MINING BUREAU. hy rail to the plant of the Sedan Calcined Ma^nesite Company at P^niervville, Cal. A total of over 1000 tons was shipped up to the end of 1918. Idle since 1919. A sample of the calcined magnesite has been presented to the ]\Iuseuni of the State Mining Bureau, by ^Mr. Frank Maestretti of the Sedan Company, accompanied by the following analysis : Analysis of Calcined Mafjnesite. Silica (SlO^i) l.ns% Iron and Alumina (R2O3) 0.40% Lime (CaO) 2.02'/, Magnesite (MgO), by difference 95.60% Ignition loss 0.90% 100.00% Quinto Claim. This claim, located by E. S. Kingslev of Gustine. is in Si of See. 32, T 8 S., R. 7 E., M. D.' M., and was worked in 1917 by the Gustine Magnesite Company, as described above. Chas. Schindler reports that he has a group of claims on a deposit of magnesite in the Arroyo del Puerto district west of Patterson. MAGNESITE IN CALIFORNIA. 103 TULARE COUNTY. In tlie ])i'<)(liU'tioii of iiiaj^iicsitc, Tnlai'e has been the premier couiily of the state, and, as California is the oiily coniinonwcalth in the I'nited States, ('xcej)t Washington, from whieh domestic snpplies are derived, tlie ontput became of national significance, particularly during the period of the war, when foreign impoi'ts Avere curtailed oi- completely cut off. The output from Tulare County for the record year, li)17, amounted to 136,ri()2 tons, valued at 51^1,238,853, a tonnage exceeding several times over that of the next largest eontributoi-. Photo No. 46 — Magnesite vein 3 feet thick, in No. 3 workings of I^indsay mine, near Success, Tulare County. Shows effect of shearing. An estimate of the monthly i-ate of ])iH)du('tion of calcined magne- site in the Porterville district during Ai)ril, llHT, was as follows: American Magnesite Co '25()0 tons per mo. Porteivillf Magnesite Co 2750 tons per mo. Tularo Mining Co 1200 tons per mo. Other shipments 1600 tons per mo. (3320 tons crude) Total SUO tons per mo. Based on the prevailing i)i'ice of .'1^32. ')() per ton for calcincHl material, this was etniivalent to a montlih- |)roduetion \alueIFORNIA. lOo unimportant until IDUU. Tlie main deposits are east of Porterville, Lindsay and Exeter, these being the railroad points from which sliipments are made. Smaller occurrences extend southerly to a point east of Terra Bella, and northwesterly to the St. John river near Kaweah. In general direction the deposits parallel the South- ern Pacific and Santa Fe railroads at distances of from one to ten miles. The geology has liecn fully covered in the descriptions of the Porterville deposits by Hess^ and Gale." and the subject has been I'HOTO No. 47 — Slickensitled magnesite showing effect of movement along the vein, in tunnel of Lindsay Mining Company. briefly treated in the chapters of the State Mineralogist's Report (1916) devoted to the Mines and Mineral Resources of Tulare County.'' The following excerpts are taken from the last named: "The magnesite occurs in a schistose serpentine mass which is Impregnated with magnesite veins and contains some basalt and diabase intrusions. The country rock is a dull, brown, serpentinized peridotite. The rock is sheeted in places and ' Me-ss, F. L., The magnesite deposits of California: U. S. Geol. Surv., Bull. 355, pp.:?!)-4!l, 190S. -Gale, II. S.. Late dcvi-lopmeiits of magnesite tleposits in California and Nevada: U. S. Geol. Sur\., Hull. ". H), pp. 50'J-51L 1914. "Tucker, W. B.. Mines and mineral resources of Tulare County: Cal. 8tate Min. Bur., pp. 14S, 149, 1916; also in Report XV, pp. 922-923. 106 CATJFORXIA STATE MINING BT'REAT. fontains givat numbers of veitical. thin iianillel \fiii.s of magnesite. Crossing the vertical veins at a small angle is a second series of veins, and a third series crosses at right angles. * * * The veins are proV)ably due to shearing, which caused cracks. These cracks then formed cliannels for surface waters and were filled with magnesite derived from the decomposition of the enclosing rock and brought by waters from a distance and precipitated. The veins are generally discontinuous and irregular, and of narrow widths." Adeline Magnesite Mine. E. F. Schrei, Lindsay, owner. The mine is in See. 24, T. 20 S., R. 27 E., I\r. D. M., 6i miles east of Lindsay and 7i miles due north of Porterville. Schrei also owns the Oinesra and Frisc'illa claims in the same Sec. 24. and the Keokuk claim in Sec. 20. T. 20 S., R. 28 E. There is a tunnel in 252 feet, alone- a maiinesite vein from 1' to 4' Avide, strikes east and dips 40" X. There are also several promising' surface showings, consisting of veins from V to 2' wide. During the war, lessees who operated this prop- erty made shipments totaling 50 cars of crude ore. After lying idle since the war period, Schrei advises us (March, 1925), that develop- ment M'ork is again under Avay and that Los Angeles parties have organized under the name of El IMirador Magnesite Company to operate the property. It is proposed to build a shaft kiln at the mine. American Magnesite Company (see Sierra Magnesite Company). This plant, built originally by the California ^Magnesite Company, was taken over in 1916 by the American ^Magnesite Company and operated (luring the Avar as a custom plant for the calcining of magm^site for the American Refractories Company of Joliet. 111. It Avas sold to the Sierra IMagnesite Company in 1920. • The Blue Crystal Magnesite Group is in Sec. 24. T. 20 S.. R. 27 E.. iM. D. M., 64 miles southAvest of Lindsay. There are four claims and a fraction, (Blue Crystal No. 1 and No. 2, YelloAv jNIetal, Kaolin King, and AVestern Fraction), Avhich are located on the Avestern slope of a hill on the east side of the mouth of Round Valley, at an average elevation of 950 feet. There is no timber on the property. A number of strong veins of magnesite of A-ery good quality out- crop in serpentine. Three of these, about fifty feet apart, approxi- mately parallel, strike northAvest, Avith steep dips, and have been opened up by open cuts and tunnels, using hand labor, a considerable amount of crucle ore having been shipped. During the Avar period an average of 15-20 men Avere employed. Tavo cars per Aveek, or 800 tons per month, Avere the usual shipments. Transportation from the mine to the railroad cost $1 per ton and the freight tariff to San Francisco Avas $8 per ton. The Avorkings in 1917 included the folloAving : Open cut 20' deep by 35' long. 16-inch vein of No. 1 magnesite, strike N. 40° W., dip 85° NE. A 100' tunnel at an elevation of 950 feet cuts a parallel vein at 80' Avhich is 12 inches Avide. This tunnel Avill ap])arently cut a 80-inch vein exposed on the surface about 20 feet farther and develop TOO' of l)acks. Another 80-inch vein exposed on top of the hill cuts across these in an easterly direction. An 80-foot open cut has been made along the vein and all ore taken out to a depth of 30 feet. A 140-foot tunnel at an elevation of 1000 feet folloAvs an 18-inch vein Avhich splits into tAvo veins, a 12-inch and a 80-inch. Tavo other 12-inch veins parallel this and are open 10' deep and 80' in length. MAGNESITE IX (AIJFORNIA. 107 The surface of the top of the hill shows a network of veins from 3 inches to 4 feet wide and a trench at an elevation of 1200 feet cuts throuirh the top of the hill on a 80-inch vein running- E. The trench is 25' deep and 50' long:. The crest of the hill could probably be (|uarried 20' x 50' by 20' deep and 10% of the material shipped. The Blue Crystal :Magnesite Group is oAvned by S. A. Hougs, Lindsay. There has been no production the past two or three years. Bihliugraphij: Cal. State Min. Bur.. Report on mines and mineral resources'of Tulare Co.. Dec. 1916: also Reports XV, p. 92-t; XVIII, p. 531. California Magnesia Company (see Harker Mine). Chamberlain Ranch Deposits. These deposits are on the Chaml)er- lain raneh. 8 miles southeast of Porterville, in Sees. 3 and 10, T. 23 S., R. 28 E., ]\I. D. M. On the west slope of a hill which runs in a northwesterly direction, there are numerous, narrow and irregular veins varying: in width from 6 inches to 12 inches. During 1916, the property Avas under lease to the California ?klagnesite Company. Idle. Selah Chamberlain, San Francisco, OAvner. BihliograpJni : Report XV. p. 926. Cross Ranch Deposit (Burr Bros. Lease). IMrs. Fhn-ence Cross, owner. Located 3 miles north of Lindsay, in See. 19, T. 19 S., R. 27 E., :\I. 1). M.. on a Ioav hill at the edge of the valley, AAdiere a large num!;er of magnesite veins occur, more or less parallel, with north- east strike. The veins are narroAv and irregular, Avith steep dips, but do not shoAv c(mtinuity. A number of tunnels Avere driven on tile veins, from 50' to 100' in length, and ore also extracted along the outcrops in several open cuts. Idle since the Avar. BlbliograpJnj : Report XV, p. 926. Deer Creek Mine (also kno\A'n as Langley-Cook Lease). It is on the Carroll raneh. in Sec. 21, T. 22 S., R. 28 E., M. D. :\I.. 8 miles south- east of Porterville. On the north slope of a hill south of Deer Creek, there are numerous, comparatively thin A'eins of magnesite cutting a dull-ln-OAvn serpentinized i)eridotite. The rock is sheeted in i)laces, and the magnesite veins .stand nearly vertical, being parallel and varying in Avidth from 10 inches to 2 feet. The.v are generally dis- continuous and irregular. The veins have been mined l)y a number of open cuts and tunnels on both the east and Avest slopes of the hill. In the tunnel on the east slope, a shaft has been sunk near the portal, on the vein. Formerl.v operated under h^ase by J. ^V. Langley and 11. ?]. Cook of Los Angeles. Avho sbipj)ed considerable ore; but has noAV been idle for several years. Cbas. Can-oil. Deer Creek. OAvner. Bibliofjraplni : n('])o\\ XV. p. 927. V. S. Ceol. Surv., Bull. 355. PI). 39, 40. De Moulin Mine (formerly Magnesite Refractories Co.; also known as Stewart Mine). This i)i'opeit\" eontaiiis KiO aei-es pui-ehas<'d from Ceo. N. Stewart, in the X.l of Se"e. 12. T. 21 S., R. 27 E., .M. D. M. It is directlv north of Porterville antl onlv al)out 3.1 miles distant. 108 CALIFORNIA STATE MINING BUREAU. Some of tlio inasnesite opened np on this property is hydrated and of rather low grade, other portions consist of No. 1 ovo. The country roek is serpentine. Mining has l)een done by luind hil)()r, and the ore shipped crude. An ore bin and chemical lal)oratory were built, and in 1916-1917 six men were employed. The production for 1916 was 3648 tons which, sold for $8 per ton. On the south side" of the hill at an elevation of 780 feet, a 400-foot tunnel shows a north shoot and raise to the surface on a vein 3' to 4' wide, by 50' deep and 80' long. This ore is more or less hydrated and is of low grade and mixed. The same vein is exposed on the north side of the hill in the 400-foot main tunnel. A 6' to 10' vein was stoped for 250' with 125' of backs. Other development consists of two ore chutes and four raises. This main vein strikes N., with vertical dip, and the ore is more or less hydrated. It is planned to run a lower tunnel. "Workings on the south side include a 20-foot prospect tunnel showing a vein 4' to 5' wide carrying 15-20% SiO, ; also two cross- cut adits. An open quarry run in for 100' at an elevation of 800' showed in the floor, ore 10' to 15' wide striking N. 30° E. Lenses of magnesite lead oflP and large blasts were used to loosen the rock. This ore is high-grade. About 100 feet of short tunnels open up low-grade veins from 4' to 25' wide. The property has been idle for several years, and is now owned by Edward De Moulin, 833 Security Bldg.. Los Angeles, formerly president of the Magnesite Refractories Company. BihJiographij : Report XV, p. 936. Diirnba Magnesite Company (Weissman Lease). From a hill near Dinuba on the Southern Pacific railroad, near the Tulare-Fresno county line, the Dinuba ]\Iagnesite Company reports having shipped 2500 tons of magnesite during 1916. Owner, J. J. Sullivan, Dinuba. Dumont Magnesite. The Dumont property consists of 1240 acres of patented land located about five miles east of Exeter in the rolling foothills. A few scattered oak trees grow on the flats. The magne- site is exposed near the crest of a large hill in Sec. 10, T. 19 S., R. 27 E., M. D. M., as veins in the serpentine. The most prominent vein has a width of 4 feet. It strikes N. 60° W. and dips 65° NE. The ore is hydrous and high in silica. Ore is exposed by an open cut 10' deep and 120' long on the crest of the hill. Below, a tunnel along the vein shows it to be 10" wide, 30' deep and 75' long. A still lower tunnel had not been driven far enough to cut the vein and the total ore in sight was estimated at 1915 tons, when visited in 1917. Shipments totaling several hundred tons crude were made by lessees in 1916-1917; but the property has been idle since 1918. W. D. Dumont, Exeter, owner. Bihliographji : Report XV, p. 927. Duncan Magnesite Mine. Magnesite veins outcrop on the Duncan ranch, in Sees. 25 and 30, T. 21 S., R. 28 and 29 E., on the South Fork of Tule River, 6 miles east of Porterville. A spur of the Southern Pacific branch line from Porterville reaches within a quarter of a mile of the property, which lies just north of that of the Hawley MAGNESITE IN CALIFORNIA. 109 Pulp and Paper Company, which company also owns the niineral rights on 48 acres of the Duncan ranch. The Duncan deposits were one time leased by 11. L. Doyle hut the lease allowed to expiiv. The California Maynesite Company also had a lease. Some ore was shipped during the war, hut the i)roperty has been idle since Owned by Claude Duncan and ]\Irs. JMatilda Duncan, Success, ( 'alifornia. Bibliography : Cal. State Min. Bur., Report on mines and mineral resources of Tulare Co., December, 1916; also Report XV, p. 927. Fairview Magnesite Mines. The Fairview, Fairview No. 1, and Last Chance claims comprise this property which is situated in Sec. 30, T. 20 S., R, 28 E., M. D. M. The locality is 6 miles or more southeast of Lindsay, the nearest town, but not over four miles from the post office of Strathmore. On the west slope of a hill, at an eleva- tion of 950 feet, a crosscut was driven to cut a 12-inch vein striking east and dipping north. On the east slope of the same hill a number of magnesite veins outcrop and these were developed by open cuts and tunnels. Owners, R. R. Gilbert and W. F. Finley of Strathmore. Idle. Bibliogvaphy : Cal. State Min. Bur., Report on mines and mineral resources of Tulare Co., December, 1916 ; also Report XV, p. 928. Gill Ranch Deposits (California Magnesite Co., Tulare Mining Co., and Sierra Magnesite Co. leases). The Lee Gill ranch covers an extensive acreage northeast of Porterville. IMagnesite deposits occur at several places on this ranch, in the trend of the magnesite belt north and northwesterly from the mines on Porterville Hill (Harker property) . At one time (about 1913-1914), the California Magnesite Company had leases on part of the property and operated three camps : one, ('Camp 4') on a series of veins 5 miles east of Strathmore, and two, C Camps 2 and 3') in Sec. 18, T. 21 S., R. 28 E., northeast of Porter- ville. At 'Camp 4' on one place a N.-S. vein of 12 inches to 2 feet in width was stoped from an adit to the surface 40 feet up, and drifted on for 150 feet. A 12-inch vein running N. 30° W., dipping NE. intersects the N.-S. vein in the adit. There are at least three other series of veins, on some of which work has been done. At 'Camps 2 and 3', a number of magnesite veins occur in brown ser- pentinized peridotite, on the west slope of a range of foothills which lie west of Frazier Valley. There are two general systems of parallel veins: one strikes N. 45° W., and the other N. 10° W., the width varying from 1 foot to 2 feet. On the west slope of the hill, two crosscut adits were driven east, cutting the N. 10° W. vein which dips 50° W. The Tulare Mining Company had a lease on a magnesit(>-bearing area in the N.| of Sec. 7, T. 21 S., R. 28 E., northeast of Porter- ville Hill. The ground has a rolling, hilly surface bare of timber. Water has to be hauled to the workings, which lie at an elevation of 1140 feet above sea-level. A number of tunnels have been driven on these veins and considerable ore shipped, crude. The veins ranged from 6 inches to 20 inches in width. One vein, striking N. 40° W. and dipping 45° SE. was opened uj) for 600 feet along the surface by open cuts; and an adit drift at its south end showed 20 110 CALIFORNIA STATE MINING BUREAU. inches of first-class ore. Mining was ])y liand drilling, and for a time a daily production of 15 tons was maintained, with 15 men employed. The work was done by contract on a tonnage basis. Zante, a station on the Southern Pacific, Avas the shipping point. The Sierra Magnesite Company now has a lease covering all of the magnesite deposits on the Gill ranch holdings. Bihliographu: Reports XV, p. 926; XVIIT, p. 531. Hamilton Ranch Deposit. There has been some work done by leasers on the J. C. Hamilton ranch in Sec. 22, T. 18 S., R. 27 E., on a hill running easterly in the Yokohl Valley. A crosscut adit was driven north on the south slope of the hill to cut a series of N. 20° W. veins of magnesite that outcrop strongly on top of the hill. The brown serpentinized peridotite is intersected by a network of small veins ranging from 6 inches to 1 foot wide. Bibliograph)/ : Report XV. p. 928. Photo No. 4 8 — View northward showing blanket veins being worked on the property of the Porterville Magnesite Company, in 1917. Plioto by C. A. Waring. Harker Mine (Porterville Magnesite Company). The magnesite deposits on the Harker property, operated for several years (1915- 1920) by the Porterville JMagnesite Company of San Francisco, were described by Hess ^ in 1908 ; but Avere first noted by Blake - in 1853. The deposit was worked continuously, but in a comparatively superficial way from 1901 to 1909 by the Willamette Pulp and Paper Company, who ceased mining after the upper ]iortion of the largest vein had been worked out. The Harker property was later acquired by the Porterville ]\Iagnesite Company, who recognized its possibil- ities and developed it to such an extent that that company for a time enjoyed the distinction of being the largest producer of magne- 1 Hess, F. L., Tile magnesite deposits of California : U. S. Geol. Surv., Bull. 355, pp. 40-46, 1908. -Blake, W. P., ItineraiT. or notes, etc : Report of explorations in California, for railroad routes to connect with the routes near the 35th and 32d parallels of north latitude, Washington, 1856, p. 2S. MAGNESITE IN CATJFORNIA. 111. silt' not alone in the I'ortci-villc district and Tulare ('ount\', hut in the -.t;!*e as well. The rounded foothills wliicii contain the mineral form a jiortion of ()40 acres owned by ]\Irs. liarn.urover (widow of ('has. S. Ilarker), of which ;M)0 aei-es are magnesite hearing'. The entire property was leased, with option to buy. to the Porterville JMagnesite Company. Title was not transferred, however, and the property reverted to the Ilarker estate, after the elose of the war-period activity. From October, 1920, to January 1, 1928, it was operated under lease by the Sierra ]\Iagnesite Company, the ore being calcined in their furnaces at PorterviUe. Since the summer of 1923, the mine and calcining plant have been under lease to Iloff & Marker, operating under the corporate name of California .Magnesia Company, K. W. Ilarker, i-esident manager, 540 Murrav Ave., Porterville. The holdings are in Sec. 17, T. 21 N., R. 28 E'., M. D. M., about 4 miles northeast of Porterville, the nearest railroad point. The work- ings are at an elevation of from 1200' to 1500'. There is no timber on the property and the water used is hauled from Porterville in tank trucks to a 12,000-gallon storage tank at the plant. l^p to and including the greater part of 1916, the Porterville com- |)any produced only crude or raw magnesite, but in June, 1910, a small rotary kiln was installed. This was later supplemented by a second and nuich larger one. The total production, of both crude and calcined, for 1916 was the e(|uivalent of 21,500 tons of crude. This figure was exceeded in 1917. The principal deposits are in two large rounded hills, where the magnesite forms, in part, a stock work of veins in brown serpentinized peridotite, resembling a bedded struc- ture; the veins varying in size from a fraction of an inch to ten feet in width. The ore was mined l)y means of open cuts, quarrying, tunnelling, and stoping, largely under contract on a per ton basis, the company furnishing the contractors with air drills. The average price was ^4.75 per ton for ore delivered to an accessible road for hauling. The prevailing wages paid in l!)17 by contractors were: Machine men $3.50 — $4.00 per day -Miners 3.00 — 3.2-5 per day Mmkers 2.75 per day In ^Vugust 1917, 225 men were working in the mine and the daily output was from 250 to 300 tons. p]lectric power drives the air compressor, and the rotary kiln. The calcining equipment includes a 7|' x 125' rotary kiln having a capac- ity of 65 tons of calcined matei-ial per day, and an upright kiln of 10 to 15 tons per day capacity. There is also a small ci'usjiing j)laiit, the e(|uii)ment of which incdudes a hammei'-mill and a bulir mill, Ihoiiiih these are otdy occasionally used, most of the product being shipped unground. There is a chain elevator to cari-y the hot ealcined material from the kilns to a 50' x 120' cement cooling floor. Steam for the oil Itui'iiers is furnished by a 30 h. j). hoi-izontal boiler, supplemented l)y a 15 h. p. upright used as a relay. The boilers are fitted with injectors but a rcday feed-water i)unq) is connected to both for emergency use. A corrugated iron building encloses the entire plant. 112 CALIFORNIA STATE MINING BUREAU. MAQNESITE IN CALIFORNIA. 113 Fuel oil is obtained from the Coalinga district. It is emptied from the railroad tank ears into a 1000-gallon reservoir at the siding in Porterville and then pumped to two 5000 gal. tanks elevated 10 feet. Auto trucks haul it from there to a 20,000-gal. storage tank at the plant. The daily consumption was from 5000 to 5500 gals., when two rotary kilns were operated by the Porterville Company. The Porterville Company maintained an ore storage yard of 12,000 tons capacity where the raw magnesite was mixed to make a standard product carrying not over 3% lime and 4% silica. The raw ore ordinarily averages 2% CaO' and 3% SiO,, while, after calcining, the product contains 5% CaO and 7% SiOa- The larger kiln was used to run a lower-grade ore carrying as high as 8% SiOg and 5% CaO. Though during the war a large part of the product was util- ized for refractories, all of the present output of the mine is used in the plastic trade. The freight rate to Chicago (Class C District) in April, 1917, was $10 per ton; to Pittsburg (Class B District) $11.50; and to New York (Class A District) $12.50 per ton. The minimum car- load is 40 tons, while average cars carry 50 tons of crude or 4() tons of calcined. Mine Development and Geology. These deposits are in the outer range of foothills, in Sec. 17, T. 21 S., R. 28 E., about 4 miles northeast of Porterville. The follow- ing description is abstracted largely from the reports of Hess ^ and Tucker,- with observations by the present writer covering the later developments. The magnesite veins stand out prominently on two rounded hills, locally referred to as 'Porterville PTill.' One of the hills, which will be referred to as the northern hill, runs a little cast of north, and the other, which will be referred to as the eastern liill, about X. 60° E. At their junction is a saddle about 300 feet below the summits. The orebodies on these two have quite distinct ciiaracteristics. The veins occur in a brown serpentinized peridotite having an apparent ))edded structure. The serpentine forms part of a metamorphic complex consisting of a small amount of fine- grained quartzite, amphibolite schist, serpentine, and other magne- sian rocks, some of which are talcose and mica-bearing. The rocks liave a general northerly strike, with a rather high (60°) easterly dip. They are cut off by a granitic mass on the south, a few hundred feet from the deposits. Several granitic dikes cut the serpentine and other rocks, but do not cut the magnesite veins, though basic (likes (amphibolites) of several varieties cut l)oth country rock and the veins. The veins are here and there squeezed to a schist. Fault- ing is common but does not divide the serpentine into the small irregular blocks which result in the serpentines of the Coast Range and many others, from tlie swelling of the rock as it changes its chemical and mineralogieal form. However, movement is evident and the magnesite is invariably crushed in the larger veins. • He.ss, F. L., The magnesite deposits of California; U. S. Geol. Surv., Bull. 355, pp. 40-46. 1908. - Tiirker. W. B., Mines and mineral resources of Tulare County ; Cal. State Min Bur., Report XV, pp. D.-^l-OSS, lOlfi. 8— :59SI)2 114 CALIFORNIA STATE MINING BUREAU. ? ^ MAGNESITE IN CALIFORNIA. 115 To the east of the hill, there is a tunnel at an elevation of 1450 feet, in which a vein 8 feet wide of tufa-like ma^nesite was encoun- tered. In this material there had been re-formed normal magnesite which was worked. These re-formed veins follow no well-defined system. They occur at such points Avhere the conditions were favor- able. The tunnel mentioned is located near a granite intrusion on the eastern portion of the projx'rty, and therefore the veins probably lack continuity. ]\Iagnesite veins in the western area : On the south of the western (or 'northern') hill, a main gash vein has been explored by a series of tunnels at different elevations, the main or lower tunnel being nearly 1000 feet long. This vein ranges in thickness from 2' to 8', and strikes N. 45° W., dipping 65° to 70° NE. An amphibolite dike 2' to 3' thick has been intruded in the serpentine near the vein and follows it a short distance. About lOO feet from the southeast out- crop of the vein it is joined by another vein of about the same thick- ness, which has a strike of N. 10° W. These Veins have been open- cut and stoped extensively. An interesting characteristic of the magnesite veins is noticed on this side of the hill, and that is that they are thicker underground than at the outcrop, and they widen out to an extent not anticipated by the thickness of the croppings; also that intersecting veins occur underground whose presence is not at all indicated by any surface croppings. These interesting veins are usually smaller than the main veins, occur at closer inter- vals, and in some cases occur so frequently as to form a stockwork of veins. Except for the 'blanket' veins which are the characteristic feature of the upper part of the northern hill, and which are described in a succeeding i)aragraph, most of the veins stand at quite a steep angle (up to 70°). The photographs reproduced herewith reveal their distinctiveness. At the top of the hill on the Avestern slope there is a large area containing magnesite veins from which considerable ore has been taken. To the north, near the top of the hill, the more important veins (two in particular) are tiat-lying, or nearly horizontal, 'blanket' veins. The exposures were easily traceable on the surface. In this area above elevations of 1550 feet on the north end, three distinct veins dipping 12° S. have been mined, and between elevations 1550' and 1500' there is a very prominent vein parallel to the others. The largest of these veins is practically horizontal in the middle i)art and somewhat uplifted at lioth ends — north and south. It extends through the hill, a distance of 362 feet, somewhat longer than broad, and from 2' to 4' thick. A basic dike flattens and spreads under a large part of the vein in a thin sheet 1' to 2' thick ; then, breaking through, it overlies the remainder of the vein. Magnesite veinlets fill cracks in the dike, but the mass of the vein is cut by it. There is nothing to show that the vein has been tilted from a more upright j)osition to its present place. It was evidently formed as it lies, flat and cutting across the vertical structure of the serpentine. "This is accounted for by supposing that there was a slow movement in the rocl ci iS 3 ^ ? si C Q; ^ * t< i a--o o "O o MAGNESITE IN CALIFORNIA. 121 Mitchell Magnesite. There is a small deposit of inagiiesite at Rocky Hill, 2 miles east of Exeter, on the Mitchell property, which produced for two months during 1916. Four men were employed and the owner, H. D. Lester of Exeter, reports that 150 tons Avas mined and sold. The mine did not pay and AA'ork was stopped. Photo No. 5o — V'erlioal kilns of tlie Tulare Mining Company (now Sierra Magnesite), at Magnesite Station, Tulare County. Montgomery Property (Davis Lease). Magne.site to the amount of 1:^02 tons is r('i)()it<'(l tt» liave l)e('n produced during 191fi from the property of P. •). S. .Moiitgomeiy, of Lindsay, undei- a lease. Tlie h'ssee is said to have received from $9 to $11 per ton for the magne- site and to have paid the owner $1.25 per ton royalty. Idle. Bibliographij : Report XV. p. 026. 122 CAIilFORNIA STATE MINING BUREAU MAGNESITE IN CALIFORNIA. 123 Oakland Magnesite Company. Address, Realty Syndicate Bldg., Oakland, Cal., C. P. Miirdock, President. This company controlled, by lease, nearly a thousand acres in two localities. On the basis of •1^0.75 per ton rovaltv a lease is held on the mineral rip'hts of 480 acres of the propei-ty of J. AV. Lanoley in Sec. 21, T. 22 S.. R. 28 E., M. D. ]\I., 8 miles by road southeast of Porterville; l)ut no work has been done recently on this property. Another 50()-acre lease included a strip 200 feet Avide sul)-leased from the Porterville ^Magnesite Company on a basis of .^1.50 per ton royalty, and the balance on property of Lee Gill, at $1.25 per ton. The tAvo latter holdings adjoin and lie in Sees. 7 and 8, T. 21 S.. R. 28 E.. 4 mih^s northeast of Porterville. The physical character of the lands ami the mineral- ization do not materially dift'er in the tAvo localities. Poth leaseholds are in the rolling foothills and contain magnesite distributed as veins in serpentinized jx'ridotite. The second-named grouj) Avas taken over in 1!)20 liy the Sierra Magnesite Company. The Deer Creek and North Mine on the Langley Leasehold in Sec. 21 was equipped for a creAv of 20 men. Over 10,000 tons was shipped from here in 1916-1917. The ore Avas mined by hand methods. 8 men being employed. It sold for $7.50 per ton. A vein of bi'OAvn magnesite averaging 20 inches in Avidth and striking X. 45° E. is here cut by other veins, AA'hite in color. The broAvn magnesite is of good quality and of an older formation than the Avhite ore. A flat vein of Avhite magnesite striking N. 70° E. shoAved about 1600 tons of probable ore. There is also a considerable tonnage in sight on the surface. Rex Plaster Company (see Sierra Magnesite Co.). Sierra Magnesite Company (see also Tulare Mining Company, Rex Plaster Company, Lindsay Mining Company, Oakland Magnesite Company, Gill Ranch Leases). This company Avas organized in 1920. and took over all of the important producing properties in the vicin- ity of Porterville, Avhich they still retain Avith the exception of the Harker Mine (Porterville Magnesite Company) AA'hich, hoAvever, they operated to the end of 1922. The Sierra Company noAV OAvns in fee the properties described in preceding reports of the State ^lineral- ogist ^ under the folloAving names : Tulare ^Mining (Company, Rex Plaster Company, Lindsay Mining Company, and mineral rights of tbe Oakland ^Magnesite Company on 80 acres adjoining the Ilarker Mine on the north. This company also has a lease on the magnesite deposits on the Cill ranch adjoining the Oakland ground on tlu' north. They also had a lease on the minei-al rights held by the flaAvley Pulp and Pai)er Company on the Duncan j)i-operty at Success, but it Avas alloAved to lapse. The frst three groups adjoin and are in the Success district 7 miles east of Porterville. Tiie Oakland-Gill group are on the north of Porterville Hill 4 to 5 miles northeast fi-om the i-ailroad station at Porterville. Recent operations have been contined nuiinly to the 'Tulare' grouml, and ])ortions of the 'Liiulsay' and the 'Gill Lease' properties, the last-named being Avorked uiulei" a contract by Ed Ci-aniei-. All calcining is done in rotai'y fui'uaces at their plant in I'oi-lerville (foi-merly American Refractories Com- ' Report XV, pp. 919-940, 1917; Report XVIII, pp. 528-535, 1922. 124 CALIFORNIA STATE MINING BUREAU. pany; also American Magnesite Company, a subsidiary of Inter- national Magnesite Company). Ore from the Success district is brought in by rail over the branch line of the Southern Pacific Com- pany, and from the others by motor truck. These various properties are here described in the order of their geographical occurrence from south to north. MINES. REX PLASTER mine. This property comprises the S.^ of B.i of Sec. 31, T. 21 S., R. 29 E., M. D. M., in the Success district^ Veins of magnesite occur in serpentine and peridotite on rounded hills with grass-covered slopes but bare of timber. The property lies at an elevation of about 1400 feet, and water is obtained from the South Fork of Tule River. Most of the veins are small and were worked largely through open-cuts, by hand labor. One open-cut at 1000' elevation showed an 18-inch vein, strike N. 20° W., dip 85° SW. ; another at 1400' a 2-foot vein, strike N. 20 E., dip 85° SE. ; another, 150' southeast of preceding, shows five 8-inch to 6-inch blanket veins dipping NW. 20° into the hill, and which were worked over a thick- ness of 5 feet; another at 200' southeast of preceding, at elevation of 1310', a 10-inch vein, strike N. 30 W., dip 75° E., also a 4-inch vein near by; also a 4-foot blanket vein dipping 25° N., overlain by a hard rock carrying grains of chromite. This last-named was also worked by open cut. On the 'Avery Lease' in the Rex Plaster property, ore was devel- oped by means of several tunnels and one x)pen cut. In an adit at 1100' elevation, two 8-inch blanket veins were exposed, strike E., dip 15° S. ; also a 12-inch vein was worked. At 1125' elevation, an adit follows a vein 1' to 3' Made separated by 6 inches of serpentine ; and in an adjacent vein having same strike, N. 20° E. and dip 75° "W., ore is exposed 1' in width, about 20' below the surface and 25' above the last-mentioned tunnel. An open cut and a drift farther north, at elevation 1130' exposed a 1' to 4' vein of first-class ore, with strike E. and dip 65° S. The principal shipments from the Rex Plaster property were made in 1916-1917, the ore being sent, crude, to the company's calcining plant at Los Angeles and utilized for plastic purposes. No work has been done since November or December, 1917. LINDSAY MAGNESITE mine. These holdings comprise 160 acres in the N.^ of S.^ of Sec. 31, T. 21 S., R. 29 K, M. D. M., situated between the 'Rex Plaster' on the south and the 'Tulare' on the north. During 1916-1917 this mine was one of the most important three magnesite operators of the district and the largest producer in Tulare County without a calcining plant, all shipments having been made crude. All work at that time was done by hand labor. The deposits were mined partly on company account and partly by contract. On company account, miners received .$3 per day, muckers .$2.75, and tool dressers .$3.50 to $4. There were 15 miners employed, with a total of 50 men, including teamsters, on the payroll. The average output was 80 tons of magnesite per day or 2000 tons per month. MAGNESITE IN CAIJFORNIA. 125 The maguesite was opened up in veins in serpentinized peridotite, on a large rounded hill, the average elevation of the earlier workings being about 1200 feet. The following workings were noted by C. A. Waring ^ in April, 1917 : averages 2' thick. (C) Ledge: two open cuts above, average 8' deep and expose 10-inch veins for 50'. (D) LOWER KELLEY tunnel at elevation of 1150' is opened for 190' along a 30-inch vein which has 125' of backs to the Kelley tunnel. (E) KELLEY tunnel at elevation of 1265' has a 250' ore shoot which averages 2J' wide. (F) Xo. 3 shoot is 240' long and w-ill average about 3i' wide. (G) No. 4 shoot splits into two shoots, 21' wide, one 300' and one 120' long. (H) Quarry on hill worked to 160' below surface where vein was 3' wide; ore shoot was 110' wide, worked on two levels 70' and 40' ; and 50' to the surface. It lies north of the Kelley shoot and has not yet been developed deeper. (I) No. 1 tunnel cut an ore shoot striking N. 40° W., and averaging 28 inches wide. Ore has been worked out in the three upper levels. The lower level or that of the tramway track, has been run 86.6' below to cut the ore shoot." Production from this property in 1916—1917 totaled in excess of 38,300 tons. The ore was trammed around the hill to a chute ('Adams Chute') 800 feet long (see Photo Xo. 52) connecting with a spur track of the Southern Pacific from the Tulare Mine branch. AVhen visited by the writer in November, 1923, a depth of 385 feet below the outcrop had been reached in a winze sunk below 'No. 7 Tunnel'. This crosscut adit cut the orebody at 868' in, from which point a drift had been run 150' N. On this level the two main veins of the Lindsay join. The winze ('No. 43') was down 64' and showed 2' of pure-white, high-grade ore in the bottom. On one wall there was a layer of a soft white mineral, which proved on analysis in the laboratory of the State Mining Bureau to be hydro- magnesite. Ore has been stoped out above No. 7 tunnel to a height of 140'. The present company has a compressor plant at the poi-tal of No. 7 to supply air for drilling. TULARE ^MINING Comi)any ground. Those holdings which wen- taken over bv the Sierra Companv in April, 1921, comprise the X.:', of See. 31, and a portion of Sec. 30, T. 21 S., R. 29 E., ]\I. 1). M. ■-Magnesite' station at the property is on a spur track southeasterly from Success Station on the Springville branch line of the Southern Pacific railroad running up Tule River from Porterville. The eleva- tion of the plant near the base of the hills containing the deposits is only 700', but the hills rise steeply (see Photo Xo. 52) from the edge of the south fork of Tule River to twice that height. Water for all needs is obtained from the river, but timber is scarce through- out the district. The portion of the hills containing the magnesite veins is a highly serpentinized rock and the occurrence is typical, embracing both large veins and a stockwork of small veins. The Tulare Company operated two oil-fired, vertical, shaft furnaces at the mine, with a cement cooling-floor and sacking i-oom below alongside the railroad track; but the present company does all of its calcining in the rotary kilns at Porterville. They have a 50-cent rate per ton on the crude ore from Magnesite to Porterville. The old shaft kilns serve as storage bins in the ore-bunker and cliute Original manuscript of this bulletin. 126 CALIFORNIA STATE MINING BUREAU. system. Jn 1917, there were 133 men employed, and the mine output was 80 tons of crude ore i)er day, from which 36 tons of calcined material was obtained. The following workin and •")(;) hei-ewitli. I'nder- 128 CALIFORNIA STATE MINING BUREAU. MAGNESITE IN CALIFORNIA. 129 ground, in some places the flat veins widen, and in others the verticals or inclined veins widen out to workable orebodies. It can be readily seen how such irregularities Avould result in an intricate maze of intersecting: workings underground. In the 'Tulare' or north section, the occurence is that of a zone of 'nodular' ore and irregular segregations in the serpentine, being a series of discontinuous or intermittent segregations. This zone has a northwest strike, with dip 60° ±: E., and is from 30' to 90' wide. In the earlier reports on this property this zone is referred to as a 'vein.' Parallel to and west of the nodular zone, there is a magne- site 'vein' which varies from a few inches to 4' in width, and west of this vein there is what appears to be an intrusive dike. The present operators ship three grades of ore from this 'Tulare' section: 'Tulare A,' 'Base Coat,' and 'Tulare Special Select.' The tirst two are calcined for plastic mixtures, and their compositions are given in a succeeding paragraph. The third is shipped, crude, to chemical manufacturers. The silica content of the 'Tulare' ore is evidently largely secondary. 'Sierra Standard' calcined material is obtained from the ores of the 'Standard' and 'Lindsay' sections. A fifth grade, designated 'Premier' is not put on the market, but is an inter- company grade utilized by the Kellastone organization. It is merely a slightly off-color 'Standard.' OAKLAND MAGNESITE leasehold. This mineral-rights lease covers a strip of ground in Sees. 7 and 8, T. 21 S., R. 28 E., between the Harker mine and the Gill property northeast of Porterville. It is in a narrow valley running westerly and extends up the slope of the hillsides both north and south. In their 'No. 22 Tunnel' on the north side of Porterville Hill near the Harker ground, ore is being taken out of a winze where the vein shows 30 inches wide. It averaged 3' wide above the tunnel level, and the ore is white and high-grade. There is a compressor plant on the Oakland ground which supplies air to both these workings and to those on the Gill Lease over the next hill to the north. To the north of the compressor there is a shaft sunk on the 'Rose' vein (so called because of its pinkish color), but no ore has been taken from it recently. GILL RANCH lease (see also under Gill Ranch, ante). The Sierra Company holds a lease covering all of the magnesite occurrences on the Gill ranch. The principal operations are at present confined to Sees. 7 and 8, T. 21 S., R. 28 E'., north of the Harker Mine. When visited by the writer in November, 1923, the work was being done l)y Ed. Cramer on a tonnage-contract basis. Compressed air and tools are furnished by the company. Cramer looks after the opera- tion of the compressor, and is paid a stipulated price per ton for the (Um; "in the bin." The compressor plant, located on the 'OaklaiKC ground, is an Ingersoll-Rand-lmperial, Tyi)e 10, ")() li. p. electric driven. AVater is hauled from Porterville for the cooling circulation, and is re-used s(» tliat the actual consumption is small. The two other compressors at the company's mines in the Success district are of this same type. Nearly a mile of pipe line carries the air over the hill, north, to the lower tunnel ("No. 60") on which Cramer was working. 9—39802 130 CALIFORNIA STATE MINING BUREAU. Tliis adit was then in 900' on a vein with NW. strike and a width averaging' 4'. It has backs of 165' to the bottom of the old stopes. Preparations were being made to raise. There are also several veins and prospects on the south face of this Gill hill adjoining the 'Oak- land' ground. One adit ('No. 15') is in 500' and has been stoped out above, but there is ore showing in the bottom. No work Avas being done there at that time. CALCINING PLANT. The calcining and grinding plant of the Sierra Magnesite Com- pany is within the city limits of Porterville, directly on a loading track on the west side of the main line of the Southern Pacific rail- road. The plant was originally ])uilt (1015) by the California Magne- site Company, being later taken over l)y the American Magnesite Com- pany, a subsidiary of the International Magnesite Company which operated the plant at Chula Vista, San Diego County, on ore from Photo No. 58 — Calcining plant of the Sierra Masnesite Company at Porterville, Tulare County. Cooling- floor at right ; testing laboratory of the National Kella.<5tone Company at left. Photo by C. A. Waring. Lower California, Mexico. During 1917-1918, this plant opt'rated on custom ore under management of the American Refractories Company of Joliet, Illinois. That company purchased crude ore which met their specifications, at 5i?8.50 per ton delivered, and supplied their eastern customers with calcined unground magnesite at a con- tract price of $32 per ton. City water is furnished the plant. The buildings are of substantial wood-frame and corrugated-iron con- struction. The crude ore is received by rail and auto truck, and dumped on the ground near the crushers, which are set below grade to facilitate feeding. The Ore is crushed in the primary jaw crusher, folloAved by a Telsmith crusher in circuit Avith a trommel, sampled, and carried by chain bucket elevators to the storage bins. The furnace feed size is ^ inch. From here it passes through the rotary kilns, the discharge falling on a mechanical conveyor which dumps the hot calcined MAGNESITE IN CATJFORXIA. 131 I 132 CALIFORNIA STATE MINING BUREAU. Plate XI. Trucks or /?./?. Qrrs N^-4 W/tee//rref jctyy Crus/rer e/ey^for Tromme/, -? ' ho/es Oversize W? 2p l^^/ree///?cf jcfyy cri/sAer Urrofers/ze r f/evctfor ~T~ Sforcrcfe im Aufvmcrf/c feeoifsr ao'x 6' /?ofefry /0//r. 5//oce/ bnck ///7//7q, o// f/ree¥ /^serve K//rr Sfee/ eYrera co/tveyor Coo/i/Tcr f/oor I T^ — I efctfe r Serc/r/zro bu/?/rer /^joer ///7eaf burMp sercAs /SO/b. eerc/ r Flow-sheet of magnesite plant of Sierra Magnesite Company at Porterville. A MA(iNESITE IN CALIFORNIA. 133 ])rO(ln('t on tlio eooliuii' platfonii, to be later sacked for sliipmcnt or loaded ill Itulk form into railroad ears. There are two rotary kilns, one 5' x 50'. driven l)y a 10-h. p. vari- able-speed motor whieh also runs a small sample crusher and grinder, and one 6' x 75' kiln, driven by a 20-h. p. motor of the same type. Only the larger one was in use in November. 1923. The speed has been reduced so that the crude ore travels through the kilns at the rate of approximately 1 foot per 2 minutes, and the capacity is 65 tons of calcined niagnesite in 24 hours when both furnaces are oper- ated. About 2.2 tons of crude ore are required to make one ton of calcined. Electric power is furnished by the Mt. Whitney Power and Electric Co. Crude oil is used for fuel in the kilns. The oil, after being raised to a temperature of 184° F., is fed to the burners under 90 lbs. pressure, with steam at 100 lbs. Consumption of oil amounts to 1.2 bbl. per ton of calcined product. A 55,000-gallon oil-storage tank is provided. The kilns are lined with fire-brick, which must be partly renewed after 12 to 18 months' use. Twenty-seven men are ordinarily required for operation of the plant, nine being employed on each of three 8-hour shifts. Other help for loading, etc., work in two shifts of nine hours each. Fine grinding of the calcined material in preparation for stucco and plaster mixtures, is accomplished in 12 buhr mills in two banks, so that 85% will pass 200 mesh. They have adopted different burnine- ranges for their several grades, and plant conditions are adjusted to accommodate these. These adjustments make for a uniformity of products. In calcining they have found that :}-inch is the maximum feed size with which good results can be obtained in the rotary kilns, and an average of ^ inch is maintained in practice. The ore remains in the kiln slightly over two hours. If the size is doubled. 4 x the time is required. In the old Tulare upright kilns, the ore i-emained 5 hours. Up to 7-inch size was fed. It was noted that there were often unburned cores, even with the outside 'overdone.' The rotary kiln yields a more uniform product. The furnace man takes a sample of the burned material over each 24 hours, and these samples are put through the series of physical tests described in preceding pages under "tests and specifications." The NATIONAL KELLASTONE CO:\IPANY of which the Sierra IMagnesite Company is an associate (being controlled by the same financial interests), has one of its stucco plants here, where stucco mixtures are prepared for sale to contractors and material dealers. All of the technical control work of the National Kellastone Com- pany is carried on at Porterville in the physical-test and chemical laboratories. Both of these laboratories are especially and com- pletely equipped for such work. Because of the high summer tem- peratures, there is a below-ground basement room under the physical- testing building for use in the summer months, so that fairly uniform temperatures may be had for testing throughout the year. Because of their careful technical control a uniform product of guaranteed behavior can be delivered. Their three commercial grades, with approximate chemical analyses are as follows (it being 134 CALIFORNIA STATE MINING BUREAU. MAGNESITE IN CALIFORNIA. 135 iiiulcrstood that the ji'nai'aiiteod physical tests arc of iiu)i-c \ital (M)uccni tlian a specific chemical composition) : 'Sierra Standard.' White or li^ht-gray color Avhen «iroun(l; INIgO 837f-859i; ; C^aO (under 4% total; .1.5% active); ALO, and Pe.O, under 1 % ; SiO. up to S'/t . Ignition loss 2^/( . Used for finish-coat stucco. 'Tulare A.' Cream color; :\lgO 85 7c -87 % ; Al.,0', and Fe.,0, 3%; CaO (37r total, 1.5% active) ; SiO, 5%-6% . Ignition loss 3%. For flooring finish coat ; also some for stucco. 'Xo. 20' or 'Base Coat' (also called 'No. 20 B. C). Color varies, dark cream, light brown, etc. IMgO 80% ; CaO 3%c ; AlgO,, and Fe,0, about 4% ; Sid, 12%-M% . Ignition loss 4% . For base coats, l)oth in stucco and tloors. In November, 1923, there were 75 men employed in the mine, and a total of 49 in the plant, laboratories, and office, including 9 in the National Kellastone unit. A larger number of men are employed in the several mines of the company during the summer months. The otificers of the Sierra Magnesite Company are: S. H. Barrows, l)resident. Chicago, 111.; J. A. Bernhard, Balfour Bldg., San Franci.sco; and at Portrrville the following — Arthur Deleray, manager; Max Y. Seaton, technical director; J. B. I'erry, mine superintendent; L. A. Laidlaw, plant superintendent; C. R. Olsen, chemist. Bibliofjrapln/: Cal. State Min. Bur.. Reports XV, pp. 919-922, 928-931, 936-940: XVII, p. 259; XVIII, pp. 531-535; XX, pp. 30-31; Bull. 38. ])]). 333-334. V. S. Geol. Surv., Bull. 355, pp. 46-48: Bull. 540, pp. 509-511. Simmons Ranch Deposit (Bartlett Lease). There are a num- ber of coiiipai-ativciy thin xciiis of magiiesite, on or near the top of a .serpentine hill about a mile south of the schoolhouse at the Simmons Ranch, 8 miles southeast of Porterville. The hill is a portion of the outside range of foothills of serpentinized rock. The country rock is a dull, brown serpentinized peridotite similar to that near Porterville. Some, but not many, of the nuignesite veins reach 2 feet in thickness for short distances, (generally they ai-e discontinuous and irregular. A small amount of magnesite of excellent quality has been mined on the west side of the hill from a nearly vei'tical vein running parallel to the course of the hill and i-anging from 10" to 18" in thickness. On the east side, near the top of the hill, arc other veins. Development has been by shallow open cuts and short adits. It was operated under lease by W. P. Bartlett. superinteiulent of the Tulare Mininu' Company. C. W. Simmons, Deer Creek, owner. Bibliograplnj : Report XV. p. 923. The Tulare Mining Company owns the E.-J of the NE.j of Sec. 28, T. 22 S.. R. 28 K.. M. D. M., in the Deer Creek ^Mining Dis- trict. This territory is southeast of Porterville and southwest of the calcining plant and mine at IMagnesite, these three points forming a triangle whose sides are about eight miles in length. There is no limber on the I'ounded hills which ToiMii the siifface. but water can 136 CALIFORNIA STATE MINING BUREAU. MAGNESITE IN CALIFORNIA. 137 l)e ol)taiiied from Deer C'reek. This property was not taken over l>y the Sierra Magnesite Company with the other holdings of the Tulare Company. The magnesite occurs as veins in serpentinized peridotite, which so far as developed in 1917, appeared to be narrow and not numerous enough to be worked with much profit by the methods used. Four men were hand mining in open cuts and sorting old dump, getting out from 6 to 7 tons per dav. The crude ore was hauled to Porter- ville. Wood Ma^esite Mine. Small magnesite veins from 3" to 12" wide are found on the southeast slope of Badger Hill in See. 6, T. 19 S., R. 27 E., M. D. M. The only work done has been by open cuts and these are shallow and cover but a small area. The property is situated 3 miles east of Exeter, the nearest town, and is owned by J. J. Hamilton, Yokohl Valley. It was leased to F. G. Hude and L. L. Wood of Lindsay, California. Idle. Bibliography : Cal. State :\Iin. Bur.. Report XV, p. 940. ];is CALIFORNIA STATE MINING BUREAU. TUOLUMNE COUNTY. Althoutih gold furnishes the major value in the mineral output of this 'Mother Lode' county, its structural and industrial mineral deposits are not to be considered unworthy of exploitation. Tuolumne ranks first among the counties of the state in the pro- duction of marble ; and limestone, dolomite and other non-metallics add to its mineral wealth. ]\Iagnesite has only recently been pro- duced in commercial quantities though there are a number of deposits in the prospective stage. Gray Eagle Magnesite Claim. Five mining claims have been located in the Chinese Camp IMining District, in iiec. 16, T. 1 8., R. 14 E., M. D. M., of which four are for copper, and one, known as the Grey Eagle claim, is for magnesite. I Photo No. 62 — Vail and MaxweU calcining plant at Chinese Camp, Tuolumne County; for handling magnesite from the Gray Eagle mine. The Grey Eagle is situated two miles from Chinese Camp at an elevation of 1250' ; and is owned by D. E. Stratton, Chinese Camp. The surface is wooded with digger pine, and a creek crosses the claim within 100 yards of the deposit. It was operated in 1922, by Cum- niings & Regan, lessees, who shipped several hundred tons of crude ore to Oakland for plastic purposes. It was taken over in 1923 under lease by H. R. Vail and John P. Maxwell, 820 Syndicate Bldg., Oakland, and Avhen visited in Novem- ber, they were building a calcining plant (see photo) on the Sierra Railway at Chinese Camp. 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 magnesite occurs as a lens along a contact of serpentine and schist, with strike N. 65° E. and dip 45° NW. It is developed through MAGNESITE IN CALIFORNIA. 139 an adit which crosscuts it at 310' in, thence a drift has t)eeji run 50'. This level is at a depth of 98' below the outcrop, and 84' ])el()W the upper drift, which Avas driven from the bottom of the shaft. In the stope the vein shows 8' to 10' in width. The shaft has a depth of 64' with a drift 80' east. Mining of the ore was being done by contract. Analyses of five or six samples taken along the outcrop, made by Curtis and Tompkins, show the following averages: Per cent SiOa 0.60 A1.0:, 0.22 Fe..Oi 1.08 CaO 1.56 MgO .. 45.40 Ignition loss 51.01 99 S7 Purity as MgCOj 94.94% Bibliography: Cal. State .Min. Bur., Heport XX, pp. 22-23. U. S. Geol. Surv.. Bull. 355, pp. 51-52. Monarch Mine Company. ^I. Pavolich of Stent, reports (^larch, 1925) uncovering a l)()dy of mairnesite 5 feet wide on this property. 1| miles from Chinese Camp. Peter Maki Claims. Three magnesite claims, the Sunshine, Snow- drift and one other, are located in Sec. 6, T. 1 S., R. 14 E., M. D. M. about one mile southwest of Chinese Camp. One claim comes up to the railroad near the railroad Avater-tank south of Chinese. The property is unecjuipped and no ore has been shipped. The owner stated he had 50 tons in a pile, luit specimens which he showed a.s an average of the pile carry considerable chalcedon\' and wouhl not be marketable. A little prospecting deveh)pment was being done in November, 1923. I'eter j\Iaki, owner. White Rock Magnesite Mine. This property is also in the Chinese Camp district, in the southwest corner of See. 6, T. 1 S., R. 14 E., M. D. ]\I. It lies on a pine-covered rounded hill. \Vat«'r lias to be hauled from Chinese Camp. The deposit looks like a vein-filling along a brecciated zone, the mineral perhaps, being carried down from the surface and recrys- tallized in veins. The magnesite vein strikes N^. 85° E. and dips 80° S. varying in Avidth from 1' to 2'. A 60' incline shaft having one compartment and mauAvay has been sunk on the vein, and it has also been open-cut along the surface from 3' to 6' for over 1000'. The vein is only a])out 1' Avitle in the bottom of the shaft and did not justify the expenditure upon it. The magnesite is of good (piality but it has been poorly mined, leaving a great deal of serpentine Avith it. xVbout one-half a car-load might be sorted from a pile laid out at the mine for shipment. There had been a 30' headframe. 1000-gallon Avater-tank, 800-gallon wooden tank, 60-h. p. steam boiler, hoist, and compressor on the property, but ruined by a fire. Three cars of ore are said to have been shi])ped from the mine to the Sedan Calcined Magnesite Company, Emeryville, California, in 1917. The property Avas leased to E. E. Schmitz and Frank Nyland 140 CALIFORNIA STATE MINING BUREAU. but the lease expired. It was later leased by Harry Van Zanter and Mr. Prentice who were to continue sinking the shaft on shares with Henry Sims, the owner. The deposit will not pay to work with the equipment on the ground and present facilities. No further commercial production has been made to the end of 1924. Henry Sims, owner, Chinese Camp. INDEX. Page 'Active' oxide 24 Adeline mine -- 106 Afton deposit 72-75 map of -- 72 outcrops of 73 Aggregates, addition of 23-25, 30 Alameda County 36, 37, 40-43 mines in 40-43 production in _- 36, 37 Albertz ranch deposits 89 Alloys of magnesium -- 20 American Magnesite Company 81, 103, 106, 124, 130 Magnesium Corporation 21 Refractories Company 106, 123, 130 Analyses of magnesite 15, 49, 56, 62, 68. 74, 95, 99, 102, 113, 126, 139 Anderson property -- 44 Arnstein lease , 79 Avery lease -- 124 Bachler mine 44 Bald Eagle claim 98 Bartlett lease 135 Battenburg Refractory Magnesite mine 89-91 Bay Cities Water Company -- 79 Bedell property 53 Berry strain gauge 33, 34 Berthenia mine 53 Bibliography (general) 39 (see also under individual mines) Bissell mine 47-50 analysis of magnesite from 49 section of -_ 48 Black Bird Valley mine 79 Blake, W. T., cited -- 110 Blanco mine 16, 53, 54, 55 Blanket veins in Marker mine 110, 112, 114 Blue Crystal group 106 Boggs property 107 Boiler-scale, prevention of 19 Bonanza mine 66 Booth, Garrett and Blair, cited 95 Borchsenius claims 98 Bradford ranch deposit 16, 78 Bradley, W. W., cited 44, 51, 95 Buckling of cement 26 Buhr mills, fine grinding in 133, 136 Burgans ranch deposit 91 Burnett ranch deposit 78 Burning, effect of, on magnesite 15 furnaces used in 22 methods of 22 Burr Bros, lease 107 Butcher mine 16 Calcining, effect of. on magnesite 15 furnaces_-_22. 42, 45, 51. 54. 58. 68, 69. 70, 84, 85, 88. 90, 96. 116, 121. 131 methods of 22 time of 133 Calcite. chemical rebition of, to magnesite 11 California (Jraphite Company 52 Magnesia Company 37, 107, m Magnesite Company _ 98. 106, 107. 109 total production of magnesite in 37-38 Carbon dioxide in magnesite 12. 15 Carbonic acid gas, utilization of 19 Carroll ranch deposit [ I07 Causes of unsatisfactory installations Ig Caustic magnesite 18 142 INDEX. Page Cedar Mountain district, early production from 37 mine 16, 40-41, 42 Cement (see also 'oxychloride') 17—18 Chamberlain ranch deposits -- 107 Characteristics of magnesite 11—13 Chart of magnesite production in California 36 Chemical and physical tests for magnesium oxychloride 21—27, 28 Chiles Vallev mines 53 Clarke, R. H -- 82, 84, 85 Cleveland mine 53 Cliffside Magnesite Company 72 Cochrane ranch deposit 16, 79 Coghlan property 118 Color of cement . -- 30 Conchoidal fracture 10, 12 Concrete design on different princinle from oxychloride cements 25 Cone lease -- SO Consistency of cement i 30 Consumption of magnesite by copiier converters 39 for plastic iiurjioses 39 in open-hearth practice , 16 of oil for fuel 51, 68, 113,133 Contracting of cement 26 Costs of magnesite production -- 39 freight 113, 125 fuel ■_ ■ 51 hauling 51, 55, 56, 58, 70, S9, 125 labor 111, 124 Cramer contract 129 Creon deposit 89 Crocker property — 41 Cross-bending tests 31—32 Cross ranch deposit : 107 Curtis and Tompkins, cited 139 Dead-burned magnesite 18 in California 54, 69, 70. 90 Deer Creek mine 107,123 De Moulin mine 107-108 Detert and Elder 16 Detert mine 53 Dinuba Magnesite Company 108 Dolomite, chemical relation of. to magnesite 12 Doyle lease 109 Dumont property 108 Duncan mine 108-109, 117 Duralite Company 76 Eakle, A. S., cited 58. 59 Eckel. E. C. cited 12. 39 Eckert ranch deposit 92 Elder, Geo. W 74 Elder mine 53 El Mirador Magnesite Company 106 Eng. Soc. Western Pennsylvania, cited 18, 39 Epsom salts 20 Expanding of cements — 26 Fairview mines 109 Fenster deposit — 99 Ferguson mine 44, 45 Fillers used 17, 23, 25 Fine grinding 23, 30, 133, 136 Fire brick 13 Fischl property 71 Plat-hearth calcining furnace 42 Flooring 18 Flow-sheet of Sierra Magnesite Company plant 132 Fresno County 36, 37, 44-46 mines in 44-46 production in 36, 37, 44 Fresno Magnesite Company 44 Furnaces 42, 45, 51, 54, 58, 68, 69, 70, 84, 85, 88, 90, 96, 116, 121, ^ll I INDEX. 143 Page Gale, H. S., cited 9, 13, 1(5. 47. tJl, fi2, 66, 83. 93,105 Ga.sh veins in Marker mine 112, 115, 117 General Electric Company, special uses of magnesite by 99, 101 Geology of magnesite deposits 47, 56-57, 61-62, 73-74. 82-83, 89, 93, 98. 105, 113-116, 126-129 Germany importations from -- 20, 23 Gilliam Creek properties 91, 96 Gill ranch deposits 109-110. 129 leases 123, 129-130 Gilmore needle for setting time tests 24, 31 Glue-joint principle 23 Grades of ore mined by Sierra Magnesite Company 129 of product marketed 135 Gray Eagle claim 138 Grinding, fine 23, 30 Guerneville Farms Company 92 Gustine Magnesite Company 98, 99-101 special, high-grade ore from 99 Hamilton property -_ 137 ranch deposit , 110 Hanks, H. G., cited . 9 Hajipy Canon magnesia claims 77 Marker Estate jirop'erties 89, 9(1-97. Ill mine 37, 110-117. 12:; blanket veins in 110. Wl. Ill gash veins in 112. 11"., 117 geology of -- 113-1 Id wages paid at 1 1 I quarry 1(1 Hawley I'ulp and Paper Company 108. 117-118 Hayden mine ' 118 Mayes ranch deposit 42 Meadberg property -_ 118 Mealdsburg Marble Company 91 Memet mine 61-64 ore sorting at 62 Mess. P. L., cited 20, 21, 52, 56. 61, 83, 90. 105. 110. 113 Mixon ranch deposit 52 Hoff and Marker lease 111 Hoff Asbestos Company 41 Magnesite Companv, Inc 79 Hoff. .John D r,5 Hoff-I'rice Company IG, 69, SI Howard Cattle Comjiany 100, 101 Huguenin. Emile 8 Humidity, effect of 25 Hydro-magnesite _- 43, 71, 125 Imports of magnesite 38-39 Industrial uses . 13—21 Innes-Speiden and Company, Inc 65 International Magnesite Company 49, 76, 124, 130 Iron, in magnesite 15, jg .lackson mine 10, 7<( .Icrome group : CG, 7] Jour. Amer. Ceramic Society, cited ;^9 Joyner Bros, mine 118 Kern County 36, 37, 47-50 mines in 47-50 production in 36, 37 Kings County, mines in 51 Magnesite Company ' 51, 53