124 J. H. Pratt — Nortlmpite^ Pirssonite, 



lake, partly filled up with salt, borax, alkali, mud and volcanic 

 sand. During the wet seasons a little water accumulates, but 

 it remains only a short time and is never over a foot or two 

 deep, while in most places it is not more than two or three 

 inches. In the smaller basin, however, the water stands con- 

 siderably longer. The larger basin is somewhat lower than 

 the other, the narrow ridge referred to above preventing the 

 waters of the smaller basin from flowing into it. 



At the present time, borax is the only product manufactured 

 from the minerals of the locality, and it is from the smaller 

 basin and the narrow ridge that most of it is obtained. Tin- 

 cal, or native borax, has been found in crystals to a depth of 450 

 feet, which is as deep as explorations with drills have penetrated. 

 ^' Crude borax " is described by Mr. J^orthup as found on the 

 surface of the higher parts of the lake, in a condition resem- 

 bling burnt bone. Underlying this is a very hard, uneven 

 deposit of different salts, which is generally not disturbed. 

 The crude borax is collected only to a depth varying from two 

 to eight inches, although the original thickness is much greater. 

 In about four years, the efflorescence of borax forms again, the 

 solution being drawn up by capillary attraction and leaving 

 the bone-like deposit on evaporation. Most of the borax is 

 obtained from this crude material, although some is obtained 

 by the evaporation of the natural solution of borax in the lake 

 water. 



The minerals described beyond were found while exploring 

 the underlying formations, and were obtained by Mr. Northup 

 after carefully working over the tailings or debris from the 

 borings. 



The minerals associated with the borax at this region are, 

 according to Hanks,* sulphur, gold, cerargyrite, embolite, 

 halite, anhydrite, thenardite, celestite, glauberite, gypsum, 

 calcite, dolomite, trona, gaylussite, natron, hanksite, colemanite, 

 tincal, soda niter and hydrosulphuric acid. To this list sulpho- 

 halite, northupite and the new mineral to be described in this 

 paper must be added. Of the foregoing, colemanite,t hank- 

 site,:j; and sulphohalite § were first derived from this locality. 



Northupite. 



A preliminary description of this mineral has been given by 

 Mr. Warren M. Foote.|| According to information received 



* This Journal, xxxvii, p. 66, 1889. 



f Bull. Cal. Acad., No. 2, Jan, 1885, and Zs. Kr. 10, p. 179, 1884. 

 X This Journal, xxx, pp. 133 and 136, 1885, also xxxvii, p. 63, 1889. 

 % Ibid , xxxvi, p. 463, 1888. 



II Proceedings of the Acad, of Nat. Sci. Phil., Sept. 1895, and this Journal, 1, 

 p. 480, 1895. 



