Mercury Mexico

Iodine occurs to a minute extent (less than 0.001 %) in sea water, but is found in greater concentration, combined in organic form, in certain seaweeds, in oysters and in cod livers. Crude Chile saltpetre, or caliche contains small amounts of sodium iodate, NalOj. from which iodine can be obtained (see below). Some insoluble iodides, for example liiose of silver and mercury(II), occur in Mexico. Iodine is found in the human body in the compound thyroxin in the thyroid gland deficiency of iodine in diet causes enlargement of this gland (goitre). 

Spain, which until 1989 was the world s largest producer of mercury, ceased mine production after 1990, although 100 t of mercury were produced in 1991 from stockpiled materials. China, Mexico, and Russia were the largest producers in 1992 (14). 

The discovery of aqua regia by the Arab alchemist Jabir Ibn Hayyan (ad 720—813) provided a new extraction technology. Amalgamation of silver in ores with mercury was extensively used during the late fifteenth century by the Spaniards in Mexico and BoLvia. In 1861 the complex ores of the Comstock Lode, Nevada, were ground together with mercury, salt, copper sulfate, and sulfuric acid, and then steam-heated to recover the silver. 

The use of mercury for extracting precious metals by amalgamation has a long history and was extensively used by Spain in the sixteenth century when her fleet carried mercury from Almaden to Mexico and returned with silver. However, environmental concerns have resulted in falling demand and excess production capacity. It is still used in the extraction of gold and in the Castner-Kellner process for manufacturing chlorine and NaOH (p. 72), and a further major use is in the manufacture of batteries. It is also used in street lamps and AC rectifiers, while its small-scale use in thermometers, barometers and gauges of different kinds, are familiar in many laboratories. 

Mercury is also found in black metacinnabar and mercury chloride. Small hquid droplets of mercury may be visible in high-grade deposits. Mercury ores are also found in Algeria, Mexico, Bosnia, and Canada as well as in Spain and California. 

MMWR. (1996b). Mercury poisoning associated with beauty cream - Arizona, California, New Mexico and Texas, 1996. Morbidity Mortality Weekly Report, 45(29), 633-635. Online. Available HTTP (accessed 5 July 2003). 

Father de Acosta told how Henrique Garces, a native of Portugal, discovered that the red substance llimpi with which the Indians used to paint their faces was the same as the Castilian vermilion. After the mines of Palcas in the territory of Guamanga had been discovered in this way, much of the mercury obtained from them was shipped to Mexico to be used in the refining of silver (232). Pedro Fernandez de Velasco, who... 

Iodides, bromides, and selenidesof mercury also occur, but rarely. The iodide has been met with in Mexico, associated with the selcnide, A specimen of the bromide Dr. Dalzell found to contain, besides bromine, traces of Iodine, selenium, and sulphur. Bost5 has described the aelenide as composed of selenium 6-49, sulphur 10-30, and mercury 81-33. 

Cinnabar occurs in veins or may be in masses in shales, slates, limestones and similar rocks due to the impregnation by mineral-bearing solutions or as replacements. The former U.S.S.R., former Czechoslovakia, Bohemia, Bavaria, Italy and Spain have furnished excellent specimens. The most important of the world s mercury deposits is at Almaden in Spain. Italy, Peru, Surinam. China and Mexico have commercially valuable occurrences of cinnabar. In the Uniled Slates this mineral is found in California (most important deposit), Nevada, Utah. Texas and Oregon. Cinnabar is the chief ore of mercury. Its name is supposed to be of Hindu origin. 

Parathion poisoning in Columbia, Egypt, Iran, Malaysia, Mexico Organic mercury poisoning in seed grains (Iraq, 1972)... 

School is an important setting for many children and adolescents. Many of the residential factors described above can apply to the school setting. However, there may be additional sources of chemicals that are associated with laboratories, activity rooms, or school equipment. For example, exposure to volatile compounds has been reported in art buildings (Ryan et al., 2002) polybrominated diphenyl ethers, used in flame retardants, were detected in teaching halls containing 20 computers (Sjodin et al., 2001) mercury intoxication resulting from use of school barometers has been reported in a number of countries (Koyun et al., 2004) and in Mexico, lead levels were higher in children who habitually bite coloured pencils (Lopez-Carrillo etal., 1996). 

Various modifications of the amalgamation process have been employed in Mexico and Chile, but in recent years this method has been to a great extent supplanted by the cyanide process, described on p. 291. Extraction by amalgamation is more difficult with silver than with gold. Mercury liberates silver rapidly from the chloride, bromide, and iodide, and very slowly from the sulphide. Other ores have to be converted... 

Centers for Disease Control and Prevention (CDC). Mercury poisoning associated with beauty cream— Texas, New Mexico, and California, 1995-1996. MMWR Morb Mortal Wkly Rep 1996 45(19) 400-3. 

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