No. 2118. ALLOPHANITE, FUCH8ITE, AND TRIPHYLITE— WHERRY. 467 



Penfield's analyses of material from the old Grafton locality and from 



Norwich, Connecticut,^ are added, in columns 2 and 3, respectively. 



The indices of refraction, detennined by the immersion method, 



and the specific gravity are also compared with the corresponding 



values of the older material. 



1. 2. 3. 



FeO 27.66 26.23' 26.40 



MnO 16.63 18.21 17.84 



CaO trace 0.94 0.24 



MgO 2.30 0.59 0.47 



U2O 8.49 8.79 9.36 



NajO 0.35 0.12 0.35 



K2O 0.06 0.32 



P2O5 43.85 44.03 44.76 



Si02 0.27 



HoO 0.41 1.47 0.42 



Total 100.02 100.70 99.84 



Sp.gr 3.531 3.520 3.534 



a 1.690 1.688 



p 1.690 1.688 



7 1.695 1.692 



7-a - 005 .004 



Sign + + 



In so far as the percentages of ferrous and manganous oxides are 

 concerned, the present mineral is closer to that from Norwich (3) 

 than to the old Grafton occurrence (2). Since the specific gravities 

 in this group vary with the relative amounts of these oxides, the 

 former jdelding the higher values, the gravity of 1 might be expected 

 to exceed that of 3. The shghtly lower figure found is probably to 

 be correlated with the relatively large amount of magnesium oxide 

 present. 



The group to which the mineral here described belongs comprises 

 triphyhte, LiFePO^, hthiophihte, LiMnPO^, natrophilite, NaMnP04, 

 and the stdl imnamed members LiMgP04, NaFeP04, NaMgPO^, 

 KMnP04, E[FeP04, etc. In accordance with the writer's plan for 

 simplifying mineralogical nomenclature ^ it is recommended not only 

 that no new names be given to the last of these, but also that Hthi- 

 ophihte and natrophilite be dropped.^ Triphyhte then becomes the 

 series name, and chemical prefixes may be applied to it to refer to 

 any desired end-member. 



The mineral from the new Grafton locality may be described, 

 accordmgly, as a triphyhte containing 60 per cent hthio-ferro- 

 triphylite, 37 per cent lithio-mangano-triphylite, and small amounts 

 of several other members of the series. 



1 Amer. Journ. Sci., ser. 3, vol. 13, 1877, p. 425; vol. 17, 1879, p. 226. 

 ' Science, new ser., vol. 39, 1914, p. 575; Proc. U. S. Nat. Mus., vol. 47, 1914, p. 504. 

 'This disregard of the " rule of priority ' ' is believed to be justified by the gain in clearness resulting froni 

 the use of names with chemical prefixes. 



