380 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 54. 



Booth, Garrett & Blair, of Philadelphia, for analysis, and the re- 

 sults, obtained by Mr. Frederick Wynkoop, of that firm, were: 



Analysis of WavelUte from Hellertown, Pennsylvania. 



AljOj 



PsOs 



F 



H20 



SiOa 



Total (less 0=r 0.3) 



36.5 

 33.4 



0.8 

 28.6 



1.1 



0.358 

 0.236 

 0.040 

 1.580 



100.1 



3.03 

 2.00 



13+ 



1. Results of analysis ; the fluorine figure is known to be too low, but the 

 material available was insufficient for its accurate determination. 2 and 3, 

 ratios. 



This agrees exactly with the Groth formula for the mineral, 

 (Al(OH,F))3(P04)24-5H20, which differs from that adopted by 

 Dana in allowing for the fluorine and in recognizing the presence of 

 an additional half molecule of water. Written in expanded form, 

 this is 3Al203.2P205.13(H20, 2HF). 



THE AXIAL RATIO OF WAYELLITE. 



A number of occurrences of wavellite have been studied crystallo- 

 graphically, but the axial ratios obtained exhibit slight variation, 

 as brought out in the following table, in which the determinations 

 are arranged in chronological order: 



» The locality was stated as "Cly, York Co., Pa.," but this Is merely the site of the factory where 

 the wavellite was used as a source of phosphorus; the mineral really came from Mount Holly Springs, 

 Cumberland County. 



This variation is undoubtedly due to the fact that the majority 

 of the crystals measured have been very minute and imperfectly 

 developed, subparallel intergrowth in particular being almost in- 

 variably present. There seems no good reason to assume that we 

 know the axial ratio of wavellite with greater certainty than ±0.005, 

 so the values should be stated only to the third decimal place; but 

 the average values given are probably very close to those actually 

 characteristic of the mineral. 



