310 Schaller — FrobahU Identity of Podolite with Dahllite. 



Analyses. 



Dabllite 



CaO 53-00 



P,0, 38-44 



CO, 6-29 



H,0 1-37 



Fe,0, 0-79(FeO) 



A1,0, 



K,0 0-11 



Na,0 0-89 



F 



Orscanic -. 



si6„ : .... 



100-89 





Podolite 



Podolite 



(crystalline 



(crystals) 



aggregate) 



51-15 



51-31 



39-04 



36-44 



3-90 



4-18 



not det. 



not det. 



3-04 



1-73 



- . - - 



0-46 



- . - - 



0-45 







0-66 



0-00 



0-26 



. _ « - 



0-56 



— 



4-87 



97-13 



100-92 ( — 0-08 for F), 



The above figui'es confirm the idea of the identity of the 

 three substances analyzed. The CO^ values for podolite are 

 somevrhat lower than that given for dahllite, btit the differ- 

 ences are slight. Water was not determined, but it undoabt- 

 edly would be present in such a secondary mineral as podolite, 

 and, moreover, a small amount must have been absorbed by 

 the sample during its pulverization. The poor suinmations 

 and the varying values in general for podolite lead one to sus- 

 pect that further analyses of purer material, carefully made, 

 would lead to slightly different results from tliose here given. 



It is hardly possible, from the data at hand, to determine 

 what is the correct formula for this interesting phosphate and 

 carbonate of calcium. A formula analogous to apatite seems 

 to be suggested by the evidence, and the 1-37 per cent of 

 water given in the dahllite analysis can be explained by other 

 means than that it is essential to the mineral, but the question 

 as to the presence of essential water can only be settled by 

 further analyses made with due consideration of all the influ- 

 encing conditions. The name dahllite has priority over jjodo- 

 lite by nearly twenty years, and the latter should, therefore, 

 give way to the older name. AVhat relation staffelite bears on 

 these minerals can hardly be settled at this time, as the proper- 

 ties of staffelite are but poorly characterized. 



Chemical Laboratorj', 

 United States Geological Sar\-ey. 



