Dr>ish and Dana — Mineral Locality at BranohviUe. 205 



closely together, now one ami now another prominent, and it 

 is nor uncommon to find five or six of the phosphates in char- 

 acteristic form on a single hand Bpecimen a few Bquare inches 

 in surface. In one such specimen, for example, we have at 

 one extremity lithiophilite and triploidite, then hnreaulite and 

 natrophilite Interpenetrated by a narrow zone of eosphorite 

 and again lithiophilite. In another specimen which gives a 



rion into the interior of a nodular mass we pass from the 

 exterior alhite through a nondescript /one blackened by oxida- 

 tion and Bhowing some dickinsonite, through distinct foliated 

 masses of the same mineral enclosing patches of natrophilite, 

 then hnreaulite abundant with fairrieldite and some reddingite, 

 and finally the unchanged lithiophilite. 



Much of the material is of the most ill-defined and problem- 

 atical character, being an intimate mixture sometimes of eos- 

 phorite and quartz, such as we have before described, or of 

 others of the phosphates in indistinct form. Typical specimens 

 of the different species are as characteristic as could be desired 

 and recognized at once; in others less characteristic they 



jemble one another so closely that identification is often a 

 matter of much difficulty. It may be added that much of the 

 triploidite can hardly be told by the eye from a massive red 

 garnet commonly associated with it, while the fairfieldite sim- 

 ilarly resembles the albite ; in these cases, however, a simple 

 test of hardness is all that is required. We go on now to a 

 detailed account of some of the more interesting species 

 identified. 



Natrophilite. 



The sodium-manganese member of the triphylite group, to 

 which we give the name natrophilite, has been identified only 

 in the material obtained during the last summer. It occurs 

 sparingly, usually closely associated with lithiophilite, and upon 

 a superficial examination could be confounded with it, although 

 distinguishing characters are not wanting. It appears in cleav- 

 able masses for the most part, the cleavage surfaces often broad, 

 and showing something of a pearly luster. Occasionally smaller 

 grains appear imbedded in the cleavage mass, and these show 

 at times a more or less distinct crystalline form. On one of 

 these the usual planes of triphylite were identified, 110, 120, 

 021, 001 (cleavage). The angles could not be obtained accu- 

 rately but were sufficient to determine the forms, viz : 





Natrophilite. 



Triphylite 



110 a110 = 



50° 30 



47° 



120 a 120 = 



87 



82 r 



001 a 032 = 



47 -49° 



40 29 



In crystalline form, then, it agrees as was to be expected with 

 triphylite and lithiophilite. Optically it also corresponds so far 



