68 
THE ROMAN COMAGMATIC REGION. 
Norm of I. 
Norm 0} II. 
Or 
. <2. 26 "* 
Ab 
I 7 2O 
78. 17 ^ 
An 
8.62 ' 
Ne 
6. 2S 
6.2s 1 
Di 
6.cx 
Ol 
I O"C ' 
7. 10 
Mt . .. 
11 
4-41 
1 . 06 
6.27 
Hm... 
Ap ... 
. 0.80 
. 0.94 
0.94 
Rest . . 
98.73 
1.36 
84.42 
I4-3 1 
50.04 } 
15.20 t 
77-47) 
12.23 ) 
5-94 
5-94) 
7-17* 
1.87} 
9.04 
3-94 t 
i-37 J 
5-3i 
o-53 
o-53 
98.29 
1.27 
83.41 
14. 
100.09 
99 -5 6 
Class 
Eatios. 
Sal 
I. 
c no 
II. 
c 61 
Order 
Fern 
F 
12 . ?I 
13.08 
'L 
K 2 O' + Na 2 O' 
4 81 
Subrane. . . 
' ' CaO' 
K 2 O' 
I. 71 
*y 
i. 80 
These two analyses are very closely alike and, corresponding to this, their 
magmatic positions are almost identical. They both fall well within the limits of 
all the subdivisions, except that of subrang, in which they are both rather near 
the sodipotassic border, almost enough so to be considered transitional, in which 
case the magmatic name would be monzonose-ciminose. As compared with the 
analyses of the fiescolal ciminose, this type is markedly higher in alumina and also 
in potash and soda, a point which will be referred to in discussing the mode. 
Mode. The modes of the two specimens analyzed were determined and may 
be discussed separately. In neither case could the colorless constituents of the 
groundmass, orthoclase, labradorite, and nephelite be accurately distinguished in 
the application of Rosiwal's method, so that these are stated together. 
CALCULATED. 
MEASURED. 
Soda-orthoclase, Or 2 Ab t 
60.7) 
H-3J 
3-5 ) 
8.8 
8.9) 
i.i ) 
4-7 
I.O 
Vol. %. 
77-8 X 
9-4 X 
9-4 X 
0.3 x 
3-i X 
2.6 
2-5 
2-5 
2.9 
5-2 
Sp. gr. 
= 202.3 
= 23.5 
= 31.0 
= 0.9 
= 16.1 
Wt. %. 
73-9 
8.6 
"3 
-3 
5-9 
Labradorite, Abj An 2 
Nephelite 
Leucite 
Augite . . 
Olivine 
Biotite 
Magnetite ... . . 
Apatite 
IOO.O 
IOO.O 
273.8 
IOO.O 
