Mineralogical Notices.» 229 
On the Identity of Arkansite of Shepard and Brookite ; by R. 
Hermann, (J. f. pr. Chem. 1, 200.)—The identity of Arkansite 
with Brookite has been shown independently by J. D. Whitney, 
Miller, Rammelsberg, Breithaupt and Descloiseaux. Hermann 
confirms the previous measurement, obtaining the prismatic angle 
100° 30’, and the octahedral angles 135° 30’, 101°, and 94°. 
His analysis afforded titanic acid 96°50, peroxyd of iron 1-00, 
protoxyd of uranium a trace, silica and gangue 2°50= 100-00. 
Specific gravity =3-79. 
_Niobie and ilmenie acids 62°25, titanic acid 2-23, zirconia 557, Ce 3:09, La 2°00, 
Y0-70, Fe 5-11, Mn trace, Oa 13°54, K, Na, Li, 3°72, F 3:00, H 05010171. G.==4208. 
According to a more recent analysis by him it contains 
Niobic acid 60°83, Titanic acid 4-90, Ce and La 15-23, ¥ 0:94, Fe 228, Ca 980, Mg 
1-46, K 0°54, Na 2°69, F 221—=100°83. 
[It is well known that fluorine enters into the constitution of cer- 
tain micas and other minerals, in some of their varieuies, an yet 
_ IN assuming in the above case that the fluorine variety of pyro- 
chlore is a distinct species or is worthy of a distinct name. | 
Mengite ; Hermann, (J. f. pr. Chem. 1, 
179.)—Breithaupt remarks that the angle of 
the prism of Mengite (d) 136° 40’, isidentical 2% 
with a prism of columbite. Another prism fel a | 
(f) gives 100° 28’, and the rhombic octahe- J 
dron (3) has the angles 150° 32’, 101° 10’, 
86° 21’. According to Rose it is a zirconia 
mineral, and it is therefore an example of iso- 
morphism. — 
On Yitroilmenite and Samarskite ; by R. Hermann, (J. f. pr. 
Chem. 1, 164, No. 11, 1850.)—Hermann still sustains his view 
. 7 , . * * 
that yttroilmenite contains the acid of anew metal ilmenium, con- 
