256 W. E. Hidden — Miner alogical Motes. 







No. 1. 



No. 2. 



No. 3. 







Green. 



Brown. 



Naresto. 







Eakins. 



Eakins. 



Blomstrand. 



Si0 2 





3-46 



3-56 



2*36 



ZrO, 





1-95 



2-19 



1-11 



U0 2 





4-13 



1-73 





UO 









3-48 



Sn0 2 



_ _ . - 



. .- _ _ 







0-08 



Th0 2 





tr. 



tr. 



2-43 



PbO 













0-68 



MgO 











0-26 



ALO, 





0-77 



1-57 



0-28 



FeO 





0-65 



2-79 



2-01 



Ce a 3 











0-96 



(La,Di)A- 





0-93 



0-77 







Ifi, 



Ei-,0, 



::! 



56-81* i 



55-43* 



30-23 

 24-34 



CaO 





0-21 



0-19 



1-09 



p 2 o 5 





30-31 



29-78 



29-23 



F 





0-06 



0-56 





Q 0. 





0-57 



1-49 



1-77 









99-85 



100-06 



Less O for F.__. 



0-23 





99-83 



Sp. grav. = 4-68 



at 24-2° C. 



4-46 

 at 24-4° C. 



100-31 



4-49 



The material analyzed by Eakins in both instances, was 

 selected with great care by the use of a lens and was apparently 

 more uniform in quality than the analyses would seem to indi- 

 cate. It is a matter of surprise that the analyses, especially 

 that of the green variety, show so complex a mixture. Cal- 

 culation shows that, the molecular ratios of the P 2 5 : (Y, Er) 2 3 

 group is as 21*34 : 21*85 and we therefore must conclude that 

 the Si0 2 is present, not as admixed quartz, but as an essential 

 acidic element in combination with the other constituents : the 

 P 2 5 being alone insufficient for even the (Y, Er) 9 O a group. 



The analysis of the green material may prove a composition 

 due to a partial alteration in the nature of pseudomorphism by 

 gradual substitution, but it seems probable that xenotimef is 

 either in truth, at times, a silico-phosphate, like some monazite 

 and auerlite ; or it is often mechanically mixed with some 



* The Y Er group includes any scandium present and in both cases has a 

 molecular weight = 260 (Eakins). 



f Prof. Penfield has lately shown by his analysis of a Colorado xenotime, found 

 in situ, that it does sometimes occur in nature in a condition of almost normal 

 purity. See vol. xlv, p. 398, May, 1893. 



