rt et a) bis | a» a 
Brush and Dana—Fairfield County Minerals. 119 
between this species and triphylite makes it possible to identify 
these three cleavages with those shown by Tschermak to belong 
to the latter mineral: the most perfect gsr fe is basal, the 
second nearly perfect is brachydiagonal, and the third inter- 
rupted cleavage is prismatic (A J=183° triphy lite Tschermak). 
The hardness is about 45; and the specific gravity, in two 
trials, 3-424, and 3-432. The color of the unaltered mineral is 
af 
tion. It has a vitreous to resinous luster, and is generally 
translucent, though small cleavage fragments are occasionally 
perfectly transparent. Fracture uneven to subconchoidal. 
ptical properties.—The optic axes in lithiophilite lie in the 
basal section or plane of most perfect cleavage, the acute 
bisectrix being normal to the aon y pinibold The axial angle 
is very | he axes being partially visible in the extreme 
border of the field in the polariscope. The angle could not be 
measured satiate ctovily except in oil (n=1°47); the result of the 
measured was as follows: 
2Ha=14° 45’ for red rays. 
2Ha=119° 30’ for blue rays. 
The dispersion of the axes is strong, v>p. The character 
of the double refraction is PONE e. The three axial colors 
are quite distinct, as follow 
fies alomicne parpliel toa (that is) @ deep pink. 
(that is) ¢ pale ereiiiaicelious 
7 “ “a ¢ (that is) b faint pink. 
Chemical composition.—The following analyses are by Mr. 
Horace L. Wells. The method was the same as that employed 
by Mr. Penfield in the Balas ier of triphylite (see beyond). 
kk Mean. Quantivalents. Ratio 
P,0;, 44°83 Pe 1 44°67 ae 314 ela ¥ 
MnO 40°80 40°9 40°86 516 
FeO —- 399 ee 402 056 ¢ 082. 2°01 2 
li,O = 8-72 8°55 8°63 “288 4 ; 
Na,O +13 16 14 002 t oe eS 
H,0 17 ‘87 82 
SiO 63 66 
99°87 oer 99-78 
The dame PAs : RO: R, O=1:2:1 proves nats to 
be a norm Ip hosphate analogous in composition to tri hylite. 
Its formula is LiMnPO, or LiPO .tMn,P,0,. This ormula 
requi 
P,0, 45-22 
MnO 45-22 
Li,O 9°56 
——— 
100°00 
