J. H. Pratt — Northiqnte^ Pirssonite, etc. 123 



Art. XY. — On Northupite ; Pirssonite^ a new mineral ; 

 Go/yliissite and Ilanksite from Borax Lalte^ San Bernar- 

 dino County^ California ', by J. H. Pratt. 



Inteoduction. 



The minerals to be described in this paper are from the 

 remarkable locality of Borax Lake, San Bernardino County, 

 California. They were brought to the author's notice, in the 

 fall of 1895, by Mr. Warren M. Foote of Philadelphia, who sent 

 one of them, the northupite, together with some of the associ- 

 ated minerals, to the mineralogical laboratory of the Sheffield 

 Scientific School, for chemical investigation. About the same 

 time Mr. C. H. Northup of San Jose, Cal., sent some minerals 

 from the same region to Prof. S. L. Penfield. Among them, 

 gaylussite, hanksite and a third mineral, which has proved to 

 be a new species, were identified. These same minerals were 

 also observed among the specimens sent by Mr. Foote. Mr. 

 Northup, in his letter of transmittal, stated that he had care- 

 fully saved all of the crystals of the new mineral, having 

 observed that they were different from gaylussite in habit, and 

 that he believed they would prove to be a new and interesting 

 species. 



Both Mr. ]N'orthup and Mr. Foote have thus most gener- 

 ously furnished material for this investigation, and the former 

 has also supplied valuable information concerning the locality 

 and mode of occurrence of the minerals. The author, there- 

 fore, takes great pleasure in expressing his thanks to both of 

 these gentlemen for the services they have rendered. 



In addition to the investigation of northupite and the new 

 mineral, some interesting data concerning hanksite and gay- 

 lussite have also been obtained. 



OcGurrence. — The Borax Lake region has already been 

 described by De Groot * and Hanks f and therefore only a 

 brief description is necessary in this article. 



This alkali lake, or better alkali marsh, is situated in the 

 northwestern corner of San Bernardino County near the Inyo 

 County line and is 72 miles from Mojave, the shipping point 

 for that district. Borax Lake proper is a small basin about 

 one mile and a half in length by half a mile wide, separated by 

 a narrow ridge from a larger basin, which is about ten miles 

 long and five miles wide, known as " Dry Lake," " Alkali 

 Flat," ''Salt Bed" and "Borax Marsh." The appropriateness 

 of these names is very apparent, for the marsh is really a dry 



* Report State Min. of Cal. 1890, p. 534. 

 f This Journal, xxxvii, p. 63, 1889. 



Am. Joue. Soi. — Fourth Series, Vol. II, No. 8. — August, 1896, 

 9 



