Page:The American Cyclopædia (1879) Volume XI.djvu/413

MERCURY 401 beds or intercalated veins, enclosed in slates and quartzites of upper Silurian age. A mass of ore nearly 100 ft. wide, called el Rosario, constitutes the largest development. The Span- ish government holds the title and has leased the mines to the Rothschilds. The average yield of all the ore is about 7'85 per cent. (See ALMADEN.) The annual production of the Spanish mines was estimated in 1867 at about 2,500,000 Ibs. At Idria, in Illyria, cin- nabar occurs impregnating beds of limestone of uncertain age. (See IDRIA.) These mines are controlled by the government, and the product in 1871 was 750,400 Ibs., and about 123,200 Ibs. of artificial cinnabar. The material is very soft, sometimes contains globules of mercury, and gives off mercurial fumes which injure the health of the workmen. In the Palatinate quicksilver ores are found at mode- rate depths distributed in the fissures of the rock apparently by sublimation. At Ripa, in Modena, cinnabar impregnates micaceous and talcose slates. At Vail' Alta, in Venetia, it occurs in the calcareous schists and in quartz- ose porphyry. Native mercury is found at Montpellier in France, disseminated through tertiary marls and calcareous conglomerate. In Chili cinnabar is found in granitic rocks, and in Peru in sandstone associated with coal. The great 'Peruvian mines of Huancavelica were worked as early as 1566. The product down to 1845 was about 1,100,000 quintals of mer- cury (101-60 Ibs. each). Of this only 66,000 quintals were produced after 1789, up to which time Humboldt gives the production as 1,040,- 469 quintals, worth at the government price $75,954,237. The present annual production of Peru probably does not exceed 200,000 Ibs. Mercury is found at many localities in Mexico, but is not extracted at present on a large scale. The great consumption of this metal in the patio process at the haciendas or metallurgical works of Mexico is supplied by importations from Spain and California. The deposits of New Almaden, 12 m. from San Jose, in Santa Clara co., California, occur in the Coast range, in a belt of altered cretaceous slates, between beds of serpentine on either side. The ore is found in a series of irregular cavities occurring without apparent connection or order. The average yield of the ore worked in 1873 at New Almaden was 7'86 per cent, quicksilver ; a large amount (something more than one half) of the material reduced in that year was tierras or poor earthy screenings, yielding 2 per cent. This reduced the general average to 4'87 per cent. The product of this property for 21J years, ending Dec. 31, 1873, was as follows : New Almaden mine ... . . 573,150 flasks, or 43,845.975 Ibs. Enriquita " 10,571 " or 808,681 " Total 583,721 flasks, or 44,654,656 Ibs. (A flask contains 76J- Ibs.) The deposit at New Almaden was first found by Indians, who used the material as a paint, and excavated openings 50 or 60 ft. into the mountain in search of it. In 1824 and afterward the Spaniards attempted to work it for silver. In 1845 it was worked first for mercury by Capt. Castillero. Opera- tions were suspended during the war, and re- commenced in 1848, and a company of Mexi- cans and English held the mine from 1850 to 1858, when they were enjoined, pending litiga- tion as to title. The value of the product up to this time had amounted, according to legal papers, to over $8,000,000, and was estimated at $1,000,000 annually. The total value of the New Almaden property was rated by the United States attorney general at $15,000,- 000. In the same neighborhood the Enri- quita, Providencia, and Guadalupe mines have been worked. In Fresno county the New Idria series of mines, including the San Carlos, Au- rora, Idria, Molino, Washington, Benada, and Victorener mines, contain cinnabar in sand- stone and slate. The Panoche Grande, in this county, is famous in the records of litigation and legislation as the McGarrahan claim. The Redington mine in Lake county is similar in formation to the New Almaden. The decrease of late years in the production of quicksilver in California, and the consequent rise in price, have led to numerous discoveries and new open- ings of mines in that state. The producing mines in 1873 are given as follows : New Al- maden, 11,042 flasks ; New Idria, 7,600 ; Red- ington, 4,200 ; Great Western, 651 ; Manhat- tan, 621 ; Summit, 75 ; American, 128 ; Napa, 199; California, 995; Phoenix, 880; Wash- ington, 197. As the price of quicksilver had risen by the end of the year to $1 20 per pound, and had averaged during the year something over $1 per pound, the product of California in 1873 may be valued at more than $2,000,000. In quantity the production was less than that of previous years. California yielded in 1867, according to the reports of the Paris exposi- tion, 3,960,000 Ibs., out of a total for #11 coun- tries of 7,083,120 Ibs. The methods employed in mining quicksilver ores present no peculiar features, except those which are incident to the great irregularity of the deposits. The theory of the reduction of the ores is simple. Pure cinnabar contains 13 '79 parts of sulphur to 86-21 of quicksilver. The general average of the ores extracted is, however, less than 10 per cent, of quicksilver; in the majority of the deposits in California not over 2 per cent. Even much poorer ore than this is worked in other parts of the world. The difference in the grade of ore depends upon the proportion of intermixed gangue or sterile rock. The cin- nabar itself is usually nearly pure. In treating it, the sulphur must first be separated 'from the quicksilver, and then, since in this process the quicksilver is vaporized, its metallic fumes must be recondensed. Two systems are em- ployed. By the first the powdered ore is heated in retorts with 50 per cent, of its weight of lime or iron filings. The sulphur combines with ^the lime or iron, forming a non-volatile sulphide, setting free the mercury, the fumes of which