Dr. Genth’s Contributions to Mineralogy, 423 
IL It . IIt, 
Phosphoric acid, 29°65 29°21 29°48 
toxyd of iron, 27 62 not ined, 
Sesquioxyd of iron, 18-45 not determined. 49°70 : 
sia, 0-03 : not determined. 
Water, 25 60 not determined. 
101°35 
The analyses afford the formula : 
10(8FeO, POs+ 8HO) +3(8Fee O + 2POs +10HO) 
11. Wavellite. 
About one mile from the Railroad Depot at Steamboat, Ches- 
ter county, Pa., wavellite has been discovered in great abund- 
ance and in beautiful varieties. By the kindness of Dr. Hart- 
man of West Chester, I have received several specimens, which 
have furnished me with the material of investigation. 
tis found in minute rhombic, sometimes stellated crystals, 
which, according to Prof. J. D. Dana’s measurement have a prism 
3° . Usually however they form stalactitic or botry- 
didal concretions coating limonite. The wavellite is often coated 
with a micaceous mineral, which I have not obtained in suffi- 
cient quantity to ascertain its composition. 
After having found by some qualitative experiments that 
phosphoric acid could be completely separated from alumina by 
issolving in an excess of caustic potash, and precipitation of the 
peephoric acid by caustic baryta, I have analyzed this wavellite 
ad os method, and satisfied myself afterwards that the separa- 
on had been complete. : 
I must add, emanate that I have not always succeeded with 
this method, but as yet do not know the reason. — 
The stalactitic wavellite from this locality contains : 
Phosphoric acid, . 84°68 p.c. contains oxygen 1944 
Alumina, - - 36°67 DA 6! 17:14 
Waa” ee ne ae 
uorine, - : trace 
99°86 
The oxygen ratio of POs: AlzOs : HO corresponds with the 
atomic ratio, 3°9:5°7 :25, which very nearly gives the formula 
8Als Oz, 2POs-+12HO, as Sonnenschein has already observed. 
12. Dufreniie. 
is mineral occurs in the green sand formation at racist : 
