304 ECONOMIC GEOLOGY 



the roasting process most of the zinc is removed, and the residuum 

 consists largely of manganese and iron oxides. These are used 

 for the manufacture of ferromanganese and spiegeleisen. The 

 largest value for this product was recorded in 1908, viz., $423,792. 



The manganese deposits of the Caucasus are among the richest 

 in the world. The principal mines are at Tchiatouri in the 

 Government of Kotais, about 126 miles from the ports of Batum 

 and Poti on the Black Sea. England, Germany, and the United 

 States are the largest purchasers. Smaller quantities are 

 shipped to France and Belgium. The total exports from these 

 shipping points during the last few years has averaged approxi- 

 mately 500,000 tons. 



Manganese ores are mined in widely separated districts in 

 India. The production now approximates 1,000,000 metric 

 tons per annum. Some of the manganese mines in the State 

 of Minas Geraes, Brazil, have been worked since 1894, with 

 an annual production of about 60,000 tons. In the States of 

 Bahia and Matto Grosso manganese ores are also mined. The 

 Brazillian ores are estimated as sufficient to supply the world's 

 requirements for several centuries. 



ZINC 



The principal source of zinc ores for 1912 came from the 

 Joplin district in Missouri, the Wisconsin district, Leadville, 

 Colorado, and Butte, Montana. According to C. E. Siebenthal 

 of the United States Geological Survey the zinc industry for 

 1912, stimulated by the prevailing high price of spelter, went 

 far beyond all preceding records in the production of spelter. 

 The production of primary spelter from domestic ores was 

 323,961 short tons and from foreign ores 14,669 tons making a 

 total aggregate of 338,630 tons. The value of this banner pro- 

 duction is estimated at $46,731,000 which is an increase of more 

 than $12,000,000 over the value of the production for 1911. 



The imports of zinc ore for 1912 were approximately 78,000 

 short tons, containing about 31,500 tons of zinc. This excludes 

 18,245 tons of lead ore from South America which contained 

 2,431 tons of zinc. This amount was not recovered in the 

 smelting of the lead. 



The imports of spelter for 1912 were the largest for many years. 

 The amount is estimated at 10,700 short tons and the value at 

 $1,202,000. 



