Role of Microbes in Genesis and Weathering of Sulfur Deposits 111 



tion of H2SO4 and a great number of sulfate minerals wliich are 

 found in the weathering zone of mines ( 12 ) . Researches have 

 been made in the mines of Akhtala near Alaverdi, Armenian 

 SSR, (10) and in some mines of hydrothermal origin in the 

 Ural district of Dektarskoje and Kzasnogvardejskoje. The 

 dropping water of tlie galleries has a pH between 1.7 and 4.1 

 with about 10^ ferrooxidans cells/ml. The water which is pumped 

 up from the mine has still a higlicr bacterial content. On the 

 average, the water contains 1.025 g Cu/L as CuS04 and 1.026 

 g/L HjSOi. Fresh ore which has not yet contact with oxygen 

 and water is free of Thiobacteriiim. 



SUMMARY 



The genesis of sedimentary sulfur beds and tlie weathering 

 of elementary sulfur and of sulfidic ores is by combined bio- 

 chemical and chemical processes. Microbes of the sulfur cycle, 

 especially desulfurizers and species of the genus Thiobocterium 

 (thiobaciUus) are active also under recent conditions in the 

 syngenetic and epigenetic genesis of sulfur beds and in weather- 

 ing processes of sulfur beds and sulfidic ores of various origin. 

 Examples from USSR are discussed. 



REFERENCES 



1. CoLMER, A. R., and Hixkle, M. E.: The role of microorganisms in acid 



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2. IvANOV, M. W.: Die Rolle der Mikroorganismen bei der Bildung der 



Sch\\-efellager in den Schwefelwasserstoffquellcn der Sergijewsker 

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Schvvefellagerstatte im Shor-Su. Mikrohiologija, 26:544-550, 1957. 



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 1960. 



