A. R. Leeds— Contributions to Mineralogy. 25 
H.=15—2. G.=2°718. Massive; color light olive-green; 
streak greenish-white; powder greasy; entirely decomposed 
by hydrochloric and sulphuric acids, the silica being left be- 
hind in an amorphous powder; in closed tube yields water ; 
B.B. turns yellow from oxidation of ferrous oxide, but quite 
infusible ; does not exfoliate ; turns flame bright yellow (soda) ; 
with calcic chloride paste strong lithium band in spectroscope. 
Composition : 
O ratio 
sid, 30°62 16°331 4 
Al,O, 21°73 10°126 3 
Fe,0, 0°42 0°378 
FeO 5°01 RES 
MgO 29.69 11°876 4°84 
Li,O 0°11] 0°0 
Na,O 0°14 0°036 J 
H,O 12°26 10°898 3°23 
The small percentage of ferric oxide is due to a superficial oxi- 
tion of some of the ferrous oxide in the mineral, and is con- 
aeenty calculated as protoxide. The presence of lithia, 
whi 
that these minerals, associated with corundum, had been for a 
long time past the object of his studies, and we shall look with 
the greatest interest to the results of his investigations in this 
direction. 
V. Moonstone from Media, Delaware Co., Pa. 
4.=65. G.=2°59. Brilliant blue reflections from surface of 
Principal cleavage; finely striated upon second cleavage sur- 
din white granular albite ; closely resem- 
Omposition: SiO® 67-70, Al?0? 19°98, Fe?0* trace, CaO 1-47, MgO 0°11, 
# an 
8.86, K,0 1:36, Ign. 0-08 = 99°56, Oxygen ratio for R, d 
H. = 5-55. G=390. L : - col - 
: . G. = 8-20. Luster vitreo-pearly; color ye 
lowish-grey ; streak dirty-white; broadly bladed and sub- 
