PETROGRAPHY. 
139 
clear, colorless nephelite, in about the same amount as the melilite, and rare sub- 
hedral prisms of this mineral are seen here and there. 
As accessories occur very small anhedral grains of olivine, few small, stout laths 
of anorthite, magnetite grains, and apatite needles. In some specimens there are 
also a few small flakes of brownish biotite. 
Chemical composition. An analysis was made of this type, which has been 
already published in incomplete form. In column II is given the only other analysis 
so far made of this well-known rock. 
Chemical Composition of Boval Albanose [Melilitic Leucitite, Cecilite]. 
I. 
II. 
I. 
II. 
SiO 2 
4.Z . QQ O. 767 
je .03 
H 2 O + 
0.4? 
O. SO 
A1 2 O 3 
16. 56 . 162 
18.72 
CO 2 
none 
Fe 2 O 3 
4.17 .026 
n.d. 
TiO 2 
O. 37 O.OO? 
FeO 
s.38 . O7<; 
10.68 
P 2 O, 
o . ?6 . 004. 
MgO 
e . 3O . 133 
r.67 
MnO 
n.d 
CaO . . 
10.47 . 188 
IO. $7 
BaO . 
O 2< 
Na 2 O 
2.18 .O3S 
1.68 
SrO 
none 
Kd 
6Q, 
100.65 
IO0.67 
I. Boval albanose [leucitite]. Capo di Bove, Latian District. Washington, analyst. Cf. 
Am. Jour. Sci., IX, 1900, p. 53. 
II. Boval albanose [leucitite]. Capo di Bove, Latian District. Bunsen, analyst. Roth, Beitr. 
Petrog., 1869, p. cii, No. 31. 
Norm of I. 
An 
8 
62 8.62) 
Lc 
41 
86 ) o > 
Ne 
Q 
94 SI ' 8 ) 
Di 
Ol 
8 
18 31.58 
Am 
7 
27 
Mt 
6 
03 f 
11 
o 
76 6 '79 
Ap. . 
i 
. 26' I . 26 
Rest 
100 
o 
5 
, 7O 
100.75 
60.42 
39 - 6 3 
Class.. 
Ratios 0} I. 
Sal 
Order. 
Rang 
Subrang . 
'Fern 
F 
'L 
K 2 O' + Na 2 O' 
'1.52 
CaO' 
K 2 O' 
CaO' 
= 4-23 
= 2.74 
Analysis I resembles those of the two preceding types of albanose, though 
H is decidedly more like that of the rock from Ticchiena. 
Mode. The sections of this type were fairly well adapted to measurement 
under the microscope, though it was often somewhat difficult to distinguish between 
the colorless minerals. The results of such a study are found below. The mode 
was readily calculated, the usual assumptions being made as to the composition of 
the augite and melilite. 
