524 MINERALOGY 



in making soap, and from its preservative properties it is used in the 

 canning of meats and vegetables and to prevent fermentation in 

 milk. 



ULEXITE 



Ulexite. NaCaB B 7 . 8 H 2 O ; a hydrous sodium calcium bo- 

 rate ; Na^O = 7.7, CaO = 13.8, B 2 O 3 = 43.0, H 2 O = 35.5 ; 

 Monoclinic, elements or angles not determined ; H. = 1 ; G. = 1.65 ; 

 Color and streak, white ; Luster, silky ; Translucent. 



B.B. Fuses easily with intumescence to a clear glass, and- 

 colors the flame yellow (Na). With Turner's flux yields a green 

 flame (B). In the closed tube yields water, and after ignition reacts 

 alkaline with turmeric paper. Insoluble in cold water, but slightly 

 soluble in hot water, yielding an alkaline solution. 



General description. Crystals very fine and fibrous, in round 

 masses, with a loose, porous texture, commonly known as snowball 

 or cotton mineral by the prospectors. It forms around the 

 cracks or small holes where the solutions escape at the surface by 

 evaporation. It is the common borate at Teel's, Rhodes', and 

 Columbus marshes, Nevada; also in Inyo and San Bernardino 

 counties, California, which are practically a continuation of the 

 Nevada field. Ulexite is also associated with soda niter in the 

 deposits* of the dry deserts of Tarapaca and Atacama, northern 

 Chili. It is probably formed by the interaction of solutions con- 

 taining borax and calcium bicarbonate. 



In commerce it is used in the manufacture of borax and boric 

 acid. 



Colemanite. Ca^B^On . 5 H 2 O ; a hydrous calcium borate ; 

 CaO = 27.2, B 2 O 3 = 50.9, H 2 O = 21.9; Monoclinic; Type, 

 Digonal Equatorial ; a : b : c = .7748 : 1 : .5410 ; p - 69 51' 

 = 001 A_100; 100 A 110 = 36 2'; 001 A 101 = 42; 001 A Oil = 26 

 55' ; 001 A 111 = 33 45' ; 001 A 110 = 73 49' ; Common forms, 

 a (100), b(010), c(001), m(110), P (111), h (201) ; Cleavage, b 

 perfect, c distinct; Brittle; Fracture, uneven; H. = 4-4.5; 

 G. = 2.42; Color, white, yellowish, or gray; Streak, white; 

 Luster, vitreous; Transparent to translucent; a = 1.586; P 

 1.592; -y = 1.614; -y - a = .028; Optically ( + ) ; Axial plane 

 J-010; BxaAC = 83 in front; 2E = 95 15'; 2V = 54 52'. 



