STASSFURT SALTS. 165 



rest upon beds of rock-salt, and it was in boring for the rock- 

 salt that they were discovered about 1857. At first they \vere 

 regarded as useless, as is indicated by the name " Abraum- 

 salzen " (rubbish salts), by which they are still sometimes 

 known. About five or six years later they were worked as a 

 source of potash compounds, and now enormous quantities are 

 annually raised and furnish almost all the potash required in 

 the arts as well as in agriculture. 



The chief compounds are classed under the following mine- 

 ralogical names : 

 Sylvine, KC1. 



Sylvinite, a mixture of sylvine, rock-salt, and kainite. 

 Carnallite, MgCl 2 KC1.6H 2 0. 

 Schoenite (Picromerite), MgS0 4 .K 2 SO 4 .6H 2 0. 

 Kieserite, MgS0 4 .H 2 (mixed with carnallite). 

 Kainite, MgS0 4 .KC1.3K 2 0, or MgS0 4 .K 2 SO 4 MgCl 2 .6H 2 O. 

 Polyhalite, K 2 S0 4 .2CaS0 4 .MgS0 4 .H 2 0. 



The substances do not occur in the pure form indicated by 

 these "formulas, but are more or less mixed with each other and 

 especially with rock-salt. Carnallite is, by far, the most 

 abundant. 



The output of Stassfurt salts is now regulated by a syndicate, 

 who limit the production and fix the prices of the various salts. 

 In 1898 the quantities in tons produced and sent out to the 

 various countries were as follows : 



Calcined 



Potassium Potassium potassium Kainite Carnallite 



chloride, sulphate, and mag. and and 



80% 90% sulphate, sylvinite. kieserite. 



Germany ... ... 70,877 679 136 722,115 60,793 



Austria & Switzerland 3,844 20 17,302 



Great Britain ... 13,481 1,818 352 26,311 229 



France ... ... 14,870 1,957 108 12,241 141 



Belgium and Holland 8,723 1,089 967 37,118 6,798 



Italy ... ... 3,924 337 149 



Sweden and Denmark 4,048 1 51,364 1 



Eussia ... ... 2,379 577 8,004 30 



North America ... 54,272 9,308 8,945 176,065 



Spain and Portugal ... 1,119 521 2,364 



Other countries ... 446 1,474 27 3,193 



Total ...177,983 17,781 10,533 1,056,226 67,982 



