402 MINERALOGY 



Lake contains in solution 22 million tons of dry sodium carbonate. 

 Near Ragtown, Nevada, crusts of trona exists over the surface of 

 Soda Lake, of sufficient thickness and strength to bear the weight 

 of a man. 



A third sodium carbonate, thermonatrite, Na^Oa . H 2 O, with 

 one molecule of water, is deposited from these solutions under fa- 

 vorable conditions. Of the three carbonates, trona is the first to 

 be deposited ; as concentration increases, the very soluble natron 

 separates, mixed with sulphates and chlorides. 



Gaylussite is deposited in these lakes near the entrance of 

 small streams or springs ; as the waters of these, carrying calcium 

 in solution, are mixed with the strong soda solution, the calcium salt 

 is deposited as gaylussite. 



All these large bodies of alkaline carbonates have been attributed 

 to the concentration of solutions from volcanic rocks, or by the 

 interaction of calcium bicarbonates in solution with alkali sulphates 

 and chlorides. 



