THE NONMETALLIC MINERALS. 401 



in it. The laj^^oons of Maricunga lie about ()4 kilometers from the 

 nearest railway station and are estimated to cover 3,000,000 square 

 meters. The boronatrocalcite occurs in beds alternating with layers 

 of salt and salty earth. 



The raw material contains, in tlu>. form of gypsum and glauberite, 

 a large amount of calcium sulphate. 



Dana also mentions ulexite as occurring also in the form of rounded 

 masses from the size of a hazelnut to that of a potato in the dry plains 

 of Iquique, where it is associated with pickeringito, glauberite, halite, 

 and gypsum. The German mineral is boracite (stassfurtite) and is 

 found in small granular masses associated with the salt deposits of 

 Stassfurt. In Italy sassolite, or crystallized boric acid, has long been 

 obtained by the evaporation of hot springs in Sienna, in Tuscany. 

 Concerning the deposits of Asia Minor little is accurately known. 

 The mineral is pandermite (colemanite), which is found in thick white 

 lumps at Suzurlu, south of the sea of Marmora. Borax or tincal, 

 from Thibet, in northern India, was probably the first of the boron 

 salts to be utilized. It is stated to be brought on the backs of sheep 

 from the lakes in which it is formed across the Himalayas to the 

 shipping points in India. 



Methods of mining and mani(facture.—A.t the East Calico Cole- 

 manite mine, in San Bernardino County, the mineral is taken out in 

 the same manner as ores of the precious metals. Inclined shafts are 

 sunk, drifts and levels run, and stopes carried up as in any other mine. 

 The material, when hoisted to the surface, is loaded into wagons and 

 hauled to Dagget, whence it is shipped to the works at Alameda. The 

 process of extracting the boracic acid is not known to the public. 



At Searles's marsh the overlying crust mentioned constitutes the 

 raw material from which the refined borax is made. 



The method of collecting it is as follows: When the crust, through 

 the process of efliorescen.ce, has gained a thickness of about 1 inch, 

 it is broken loose and scraped into windrows far enough apart to admit 

 the passage of carts between them, and into which it is shoveled and 

 carried to the factory located on the northwest margin of the flat, 1 to 

 2 miles away. 



As soon as removed, this incrustation begins again to form, the 

 water charged with the saline matter brought to the surface by the 

 capillary attraction evaporating and leaving the salt behind. This 

 process having been suffered to go on for three or four years, a crust 

 thick enough for removal is again formed, the supposition being that 

 this incrustation, \i removed, will in like manner go on reproducing 

 itself indefinitely.^ 



1 In order to determine the proportionate growths of the various salts contained in 

 this crust while undergoing this recuperative process, analyses were made on samples 

 representing respectively six months', two, three, and four years' growth. From the 

 NAT MUS 99 26 



