124 
THE ROMAN COMAGMATIC REGION. 
the sections there is a very small amount of yellowish melilite in interstitial patches, 
marking a transition toward the boval type to be described later, but this mineral 
here is quite negligible. Glass does not seem to be present, at least to a notable 
extent. 
Chemical composition. An analysis of this type was made from the quarry at 
Monte Jugo, the specimen being selected from this small flow so as to furnish a basis 
of comparison with Ricciardi's analysis, without chance of great differences in the 
results due to variations in the mass of rock. For this purpose his analysis of the 
same rock is also given in II. 
Chemical Composition of Galeral Albanose-jugose [Leucitite]. 
I. 
II. 
I. 
II. 
SiOj 
4.7. ?Q O. 7QO 
48. 3O O. 80? 
TiO 2 
i .41 . 018 
A1 2 O 3 
14. 70 . 14^ 
I?. 07 .148 
ZrO 2 
O. O4 
Fe 2 O,.. 
3. IO .OIQ 
I . C 3 . OOO 
P,Oc . 
O./lC O.OO3 
O.47 O.OO? 
FeO 
<c . 08 .071 
9.18 .128 
SO, . . 
none 
MgO . . 
6. 77 . 160 
7.48 .187 
s 
none 
CaO 
11.61 .207 
I^.CK .240 
(Ce,Di) 2 O 3 . 
o.os 
Na 2 O 
I 4O . O24 
O OJ. .OI^ 
MnO 
n.d. 
O 2O 
K 2 O 
6. 03 .077 
1.73 .018 
BaO 
O. I? 
H 2 O + 
o. 77 / 
SrO 
o. 04 
Ho 
r\ 08 C 
1.78 
CO, 
none 
100.35 
100.72 
I. Galeral albanose-jugose [leucitite]. Monte Jugo, south of Montefiascone, Vulsinian District. 
Washington, analyst. 
II. Same rock. Same locality. Ricciardi, analyst. Cf. Klein, Neu. Jahrb., B. B. VI, 1889, p. 20. 
Or 
Norm Oj 
8 
f 7. 
06 ) 
An 
13 
34 1 
21.40 
) 
Lc 
53-73 
Ne 
6 
R" f 
32-33 
) 
Di 
33 
or ) 
01 
4 
04 \ 
37-05 
Mt 
IT ) 
11 
2 
71 
7-15 
45-21 
Ap. . 
I . 
OI 
1 .01 
Rest 
98 
I 
94 
23 
Class 
Order 
Ratios of I. 
Sal 
Fern 
F 
L 
= 0.66 
Rang . 
Subrang 
CaO' 
K 2 O' 
'Na 2 O' 
= 3-4 
loo. 17 
This analysis differs from all those previously given in the lower alumina and 
higher lime, this change marking the position of the rock in the salfemane class. 
As regards the magmatic position the type is well toward the center of the various 
divisions, except in that of rang, where it stands almost exactly on the border between 
rangs 7 and 8, so that the subrang is transitional between jugose (III. 7. 2. 2), where 
it belongs strictly, and albanose (III. 8. 2. 2). 
Analysis II resembles I rather closely in silica, alumina, magnesia, soda, and 
phosphoric oxide, but differs to a very marked extent in the oxides of iron, espe- 
