GEOGRAPHICAL DISTRIBUTION
Europe.
—The largest and richest deposit of quicksilver ore known is at Almaden, in central Spain. There are three nearly parallel ore bodies standing vertically side by side, each consisting of a portion of a bed of quartzite of Silurian age, impregnated with cinnabar. The ore bodies have been mined to a depth of 350 meters. The production in 1917 was probably about 25,000 flasks. The mine is said to have ore opened up that insures a future production of at least 40,000 metric tons of quicksilver. Other productive deposits in Spain are those near Oviedo, where the ore, which contains cinnabar, pyrite, orpiment, and realgar, is said to average about one-third of 1 per cent. of quicksilver, with arsenic compounds as by-products. According to a report from Vice Consul General H. A. McBride, written in Barcelona in 1911, the principal companies operating in the Oviedo districts were the Oviedo Mercury Mines Co., Ltd., of London, the Sociedad Fabrica de Mieres, of Oviedo, and the Sociedad Union Asturiana, of Mieres. The production from the district in 1915 was 608 flasks (20.7 metric tons). A third group of deposits lies on the south slope of the Sierra Nevada in the provinces of Granada and Almeria, southern Spain. The production from Granada in 1915 was 41 flasks (1.4 metric tons).
A small quantity of quicksilver was produced in Portugal in the nineteenth century from a mine not far from Lisbon. Cinnabar occurs at a number of localities in France and also in Corsica, but the deposits are not of economic character.
In South Germany, north of Zweibrucken, are quicksilver deposits that had considerable importance near the end of the thirteenth century, but at the beginning of the World War the mines had been closed for many years. Zinc ores mined near Bensberg, east of Cologne, yield annually about 90 flasks of quicksilver, won as a by-product in zinc smelting. In the former Austrian Empire the principal deposit is at Idria, about 28 miles from Trieste. The ore body occurs chiefly as an impregnation of Triassic dolomite and shale. The output in Austria in 1916, probably all from Idria, is believed to have been about 25,000 flasks. Reserves capable of yielding 20,000 metric tons, or 587,733 flasks, are known. At latest reports these mines were in the possession of Italy. At Zips, in northern Hungary, quicksilver is obtained as a by-product from iron ore (siderite) that carries mercurial tetrahedrite and some cinnabar. The production in 1913 was 2,615 flasks.
To the west of Idria, quicksilver deposits belonging to the same general belt of metallization extend into northern Italy. The principal deposit of this belt in Venetia is the Vallalta. The mine produced 9,550 flasks (325 metric tons) between 1856 and 1870, but has long been idle. The most productive deposits of quicksilver in Italy are those of the Monte Amiata district, in Tuscany, about half way between Rome and Florence. Monte Amiata is apparently a post-Pliocene volcano, and traces of recent volcanic activity survive. The most productive mine is the Abbadia-San Salvatore, which yields about 65 per cent. of the output from the district, which in 1917 amounted to about 29,300 flasks.
At Mount Avala, near Belgrade in Serbia, deposits of quicksilver ore have been known since 1883, which resemble many of those in California. The Avala deposits were worked between 1889 and 1895, but seemingly have not been productive in late years.
The only quicksilver deposits of note in European Russia are those in the Donetz coal basin, southern Russia. The essential mineral is cinnabar, accompanied by stibnite and pyrite. The deposits were discovered in 1879, the maximum output, 18,102 flasks (616 metric tons), was reached in 1897, and work was abandoned in 1911, but has been resumed since in a small way.
Asia.
—The Konia mine, in south-central Asia Minor, is in silicified limestone. The quicksilver occurs as cinnabar and most of the ore carries from 1 to 2.5 per cent. of the metal. The known reserves were estimated in 1908 at 13,000 metric tons of 1 per cent. ore. The production in 1911 was only 90 flasks of 75 pounds. The Kara-Burnu mine, said to be the only important quicksilver mine in Turkey, is situated southeast of Smyrna. In 1906 and 1907 the mine was producing about 3,000 flasks annually, but of late years the output has declined and in 1912 amounted to only 811 flasks (31 metric tons).
The Ildekansk quicksilver mine, in southeastern Siberia, east of Lake Baikal, has gained notoriety from the fact that political exiles were condemned to mine the ore. The deposit appears to be of slight economic importance.
That quicksilver deposits occur in the Province of Kweichow, south-central China, has long been known, but the locality is remote from ordinary routes of travel and comparatively little is on record concerning their character. The ore bodies of the Wan San Chang mines are the most extensively worked. For several years prior to 1905 the output averaged about 4,000 pounds of quicksilver a month. This would be equivalent to about 640 flasks annually. More recent figures of production are not available.
North America.
—The quicksilver deposits of North America are confined to the Cordilleran region from Alaska to Central America. The most productive deposits are in California and western Texas. In Alaska minerals containing quicksilver have been found in a number of the placer-mining districts, but deposits in place have been discovered in the central Kuskokwim region only. The ore occurs as cinnabar accompanied by stibnite, quartz, and a ferruginous dolomite. Development has been hindered by transportation difficulties, and only a few hundred pounds of quicksilver have been produced for local consumption. In Washington quicksilver ores have been prospected in various places, but the production is as yet inconsiderable. In Oregon cinnabar is widely distributed, but only one deposit (at Blackbutte, in Lane County) is at present productive. In the Black Butte mine the ore averages about 0.25 per cent. of quicksilver, and the quantity available above the 500-foot level is estimated by the company at about 150,000 tons. The production of Oregon in 1917 was 388 flasks, all but 3 flasks being from the Black Butte mine.
In California the principal deposits occur in the Coast Ranges within a belt that is about 400 miles long and has a maximum width of about 75 miles. The known deposits within this area are numerous. About twenty-five of these are at present productive, while probably three times that number which were once productive are now idle. With a few exceptions, the deposits of this main quicksilver belt are in rocks of probable Jurassic age, or in serpentine which is the alteration product of peridotites. The most notable exceptions are the deposits of the Oceanic mine, San Luis Obispo County, and of the Sulphur Bank mine, in Lake County. Many of the most productive mines of the past have yielded no quicksilver from underground work for years.
The most productive mine in California at present is the New Idria, in San Benito County, which in 1917 yielded 11,000 flasks out of a total for the state of 23,733 flasks and for the United States of 35,954 flasks. The New Idria ore comes from two mines, the New Idria proper and the San Carlos. The New Idria has been extensively opened to a depth of about 1,000 feet. In the San Carlos practically all of the known ore lies within 200 feet of the surface. The two mines contributed nearly equally to the total production in 1917, and the average winnable tenor of the ore in that year was 0.32 per cent. It has been estimated that in the two mines there is available 2,400,000 tons of ore averaging 0.253 per cent. of quicksilver.
The New Almaden mine is in Santa Clara County. At present, all the levels below the 800-foot are under water and of late years very little ore has been taken from the old mine. Most of the recent production of the New Almaden Co., Inc., which for 1917 amounted to 2,683 flasks, has come from the El Senador mine, northeast of the old mine, and from quicksilver recovered from ground under old furnaces and condensers. In the New Almaden, the El Senador, and in the neighboring New Guadalupe, which produced 3,100 flasks in 1917, the ore occurs as irregular bodies in serpentine. Close to the mine now being worked by the New Guadalupe Mining Co., and owned by the same company, is the original Guadalupe mine, once highly productive but now long idle.
The Oceanic mine, in San Luis Obispo County, ranked fourth in productiveness in California in 1917, with an output of 1,246 flasks. The ore occurs as an impregnation of sandstone. The average winnable tenor of the ore in 1917 was 0.185 per cent. Other mines in California which yielded from 500 to 1,000 flasks in 1917 are the Great Eastern, the Cloverdale, and the Culver-Baer, all in Sonoma County. Those whose output was between 400 and 500 flasks are the St. Johns, and the Helen, in Lake County.
Nevada contains many widely scattered deposits of quicksilver ore, no one of which has yet been worked on an extensive scale, although a few have been fairly productive for short periods. The ores occur in rhyolite of Tertiary age and in limestone or associated sedimentary beds of various ages from Paleozoic to Mesozoic. The total yield from Nevada in 1917 was 997 flasks, nearly half of which came from the Farnham and Drew mine, east of Mina, which closed for lack of ore near the end of the year. The next mine in point of yield, the Goldbanks, in Humboldt county, is also at present non-productive.
In Texas the principal quicksilver deposits are in the Terlingua district, in Brewster County. The ore occurs along fissure zones in Cretaceous limestones and shales, generally in proximity to intrusive rock. The principal mines are the Chisos, Mariposa, Big Bend, and Dallas.
In Mexico quicksilver deposits in the states of San Luis Potosi, Guerrero, and Durango are said to be yielding considerable quicksilver, even in the present disturbed condition of the country. A quicksilver dealer, testifying at the Tariff Commission hearing in San Francisco, on June 26, 1918, said that 400 flasks a month was being exported into the United States, but a considerable part of this was probably reclaimed quicksilver that has been used in the amalgamation of silver ores.
South America.
—Quicksilver deposits are known in Colombia, Ecuador, Bolivia, Chile, Brazil, Argentina, and Peru, but only those in Peru seem to be of present economic importance, and the production of that country in 1916 was only 62 flasks (2.1 metric tons). The most famous deposits in Peru are those at Huancavelica, particularly those of the Santa Barbara mine, on the east flank of the western chain of the Andes. These have been worked since 1566 and are said to have yielded 46,500 metric tons (1,366,480 flasks of 75 pounds) before 1790. The production in the 19th century has been estimated at 3,500 metric tons (102,865 flasks). The ore bodies are numerous, irregular, and occur in stratified rocks that are cut by igneous rocks. In 1916 the greater part of the quicksilver-bearing ground in the Huancavelica district was purchased by E. E. Fernandini, of Lima, and there appears to be some prospect of a resumption of active mining.