POTASH SALTS AND OTHER SALINES IN THE GREAT BASIN REGION. 33 



nitrate from traces to appreciable amounts has been shown. No deposits of economic 

 importance have as yet been discovered in the basin region and the outlook for any 

 important discovery in the future is not promising. 



BORATES. 



Borates occur in many localities in the basin region; in fact, they may be said to be 

 foxmd in the western half of the basin region from Oregon to the Mojave Desert. There 

 is a conspicuous lack of borates in the eastern half of the basin, although traces of boric 

 acid have been reported in the analyses of the waters of Great Salt Lake.^ While the 

 borate radical has not been reported in river waters, there is no doubt that it exists 

 in most of the basin streams in minute quantities. The borate radical has been 

 reported in Harney, Mono, Large Soda, Summer, Fossil, Christmas, North Alkali, 

 Middle Alkali, South Alkali, and Abert Lakes. In most of these lakes it is present 

 in very small amounts, but in Mono, Owens, and Large Soda Lakes it is present in 

 quantities ranging from 16.37 in Mono to 29.91 parts per hundred thousand in Owens 

 Lake. It has been reported in the waters of hot springs. The water of Steamboat 

 Springs, Nev., contains 21.7 parts per hundred thousand boric anhydride. A more 

 detailed examination of the waters of hot springs in the basin region would undoubt- 

 e41y show many other examples of the presence of borate minerals. Borates are dis- 

 charged into lakes by river and seepage waters. 



The workable deposits of borax are of two types — the marsh, playa, or dry-lake 

 type, and the bedded deposits. The former occur in Rhodes, Teels, and Columbus 

 Marshes, Nev. ; in basins along the Amargosa River, in Death Valley, Saline Valley, and 

 Searles Lake, Cal. ; at Sand Springs and Fish Lake Valley, Nev.'; and in the district 

 immediately south of Alvord Lake, Harney County, Oreg. The latter occurs at 

 Furnace Creek, Ryan, and at Borate, in the vicinity of Dagget, Cal. The bedded 

 deposits are found in Tertiary lake beds. 



The playa deposits have many features in common. They occur usually as periph- 

 eral deposits about the sink of an inclosed basin. They are formed by the action 

 of drainage waters dissolving the borate minerals from the alluvial material surround- 

 ing the sink. Where the drainage water strikes the more or less impervious silts of 

 the central part of the basin, it is deflected toward the surface and if it accumulates 

 sufficiently to reach the zone of surface capillarity it is drawn to the surface and by 

 evaporation leaves the soluble salts as surface incrustations and efflorescences. These 

 salts accumulate and in time form workable deposits. The crusts are scraped up and 

 hauled to treatment plants in which the crude borax is separated from mechanical 

 impurities and associated salts. The deposits are slowly renewed. This fact is well 

 illustrated by a series of analyses of crusts taken from Searles Marsh and given in the 

 following table : 



Analyses of renewed efflorescences of borax at Searles Lake} 



Constituents. 



6 months. 



2 years. 



3 years. 



Per cent. 



Per cent. 



Per cent. 



58.0 



55.4 



52.4 



5.2 



5.0 



8.1 



11.7 



6.7 



16.6 



10.9 



10.0 



11.1 



14.2 



12.9 



11.8 



4 years. 



Sand.. 

 NaCOs 

 NajSO, 

 NaCl.. 

 Borax. 



Per cent. 

 53.3 

 * 8.0 

 16. 0' 

 11.8 

 10.9 



1 lOtli Annual Report, Cal. State Mineralogist. Analyses by C. "W. Hake. 



Deposits of this character derive their borate minerals from alluvial material. The 

 disintegration and erosion of the Tertiary lake beds account for a part, at least, of 

 the borate in the alluvial material of a number of the deposits mentioned above. 

 The general prevalence of volcanic rocks and evidences of late volcanic activity 

 may well account for the remainder. 



Recent deposits of borax at depth are shown by the borings in Searles Marsh. The 

 borate minerals are associated with other salines. They have been found not only 

 in the marginal portions of the sink, but also in the central part. C. E. Dolbear^ pre- 

 sents analyses of the material taken from two borings — the first, within the central 



» Bui. No. 491, U. S. Geol. Survey, p. 144. 

 s Eng. and Min. Jour., Feb. 1, 1913, p. 260. 



20814—14- 



