Church — On Native Phosphates of Aluminium. 557 



may be useful to give here some additional evidence as to the exist- 

 ence of the fourth member of this group. Its formula is that commonly 

 given to "wavellite, but may perhaps more properly belong to the 

 Striegisane of Breithaupt. 



§ XI. Striegisane. — It was very difficult to select for analysis 

 sufficient of this mineral without including some small specks of the 

 slaty gangue. But as the weak acid used to dissolve the phosphate 

 may be assumed to have been practically without solvent action on the 

 gangue, the errox's due to traces of the latter may be eliminated by 

 recalculating the percentages after deducting the insoluble silicious 

 residue. The results of my analysis are here given : — 



Anal. 7. "443 gram striegisane in vacuo over HsSO^ 



lost -0082 ,, H.O =81-5% 



„ -1188 „ II2O on ignition =26-81% 

 gave '018 ,, insoluable matter = 4 "06%. 



Anal. 8. '2215 ,, striegisane 



gave -075 „ AI0O3 = 33-86% 



„ -002 „ Fe^Oa = -90% 



„ -114 „ Mg3P,0v = 32-90% PA. 



These percentages, after deduction of gangue, become — 

 HoO lost in vacuo 1-92% 

 HoO „ on ignition 27-94% 

 FeA „ „ -93% 



AlA „ „ 35-29% 



PA „ „ 34-31% 



100-39.% 



The above 27'94% water lost on ignition really includes some 

 fluorine ; how much, the scarcity of the mineral prevented me from 

 determining. If it did not exceed two per cent., then this specimen of 

 striegisane, though clearly related to wavellite, may perhaps serve to 

 strengthen the view that two minerals, differing merely by 1 aq., 

 have hitherto been included under that species. The 2% water lost 

 'in vacuo and the absence of any further change at 100° are characters 

 of wavellite to which species Erdmann^ long since releglated Brei- 

 thaupt' s striegisane. Possibly the kalk- wavellite of Kosmann^" may 

 belong here. At all events I find in it a mere trace of lime, and a 

 rather high percentage of water retained at 100°. 



§ XII. Peganite, Sfc. — Amongst the numerous minerals or mineral 

 varieties which have been " split" into species by some mineralogists, 

 and by others "lumped" under wavellite, there is one which has 

 been found at Nobrya in Portugal, and which very closely resembles 

 some specimens of peganite. In looking over my Striegis phosphates 

 I noticed a specimen which seemed to belong here. The amount 



3 Schw. J. L\ix., 154. lo l_ q. (jes. .xxi., 796 (1869). 



