PETROGRAPHY. 
Chemical composition. For the analysis of tavolatal appianose a whole hand 
specimen was crushed and sampled, so as to obtain representative material without 
an undue amount of groundmass. The analysis is remarkable for the very high 
potash, which is exceeded only by that in some of the analyses of orendose from 
Wyoming. The analysis by Aichino of the same rock varies widely from mine in 
many important particulars. It was probably made on unrepresentative material, 
containing relatively too much groundmass. This, however, would not account 
for the inverse ratio of the alkalis as compared with I, and as the microscopic 
examination shows that potash is present in greater amount than the soda (even in the 
groundmass), it would seem to be possible that the figures for the alkalis in II have 
been accidentally interchanged, as has happened in other cases. The other discrep- 
ancies of note are also difficult to account for, and the analysis can not be regarded 
as very trustworthy. 
Chemical Composition of Tavolatal Janeirose-appianose [Leucite-tephrite, Tavolatite]. 
I. 
II. 
III. 
IV. 
SiO 2 
CQ. 2? 
.8-18 
Cl .42 
C2 . c.4 
A1 2 O 3 
21 .41 
. 2IO 
i8.e,7 
24. 27 
20. 29 
Fe 2 O 3 
1.76 
.Oil 
n.d. 
I . II 
1. SO 
FeO. . 
1.82 
O2C 
8.47 
MgO 
O. 11 
.008 
0.48 
0.08 
O 22 
CaO 
4.48 
.080 
2. 74 
O. 71 
I 6S 
Na 2 O 
<;.i6 
.084 
10. 38 
8.62 
8 40 
K 2 O 
IT 12 
. I2O 
6. J.2 
8.87 
9 81 
H 2 O+ 
0.62 / 
f 
I . OQ 
o oo 
H 2 O- 
O. 34 ) 
0.88 
O. 14 
O. IO 
CO 2 
O 12 
o. 20 
O. 2S 
TiO 2 
O. 1:7 
.OO7 
O. 2O 
ZrO 2 
O.O2 
P,O<... 
O. 12 
.OOI 
O. 14 
O.O6 
so,.... 
O.Os 
.Oil 
O. 71 
O.67 
a... 
o 18 
OO6 
O 7O 
MnO 
nd. 
trace 
n.d. 
trace 
BaO 
O.It 
O.OQ 
SrO 
trace 
0.07 
O = C1 
99.86 
0.05 
100.23 
99.87 
*ioo-58 
0.27 
99.81 
100.31 
Sp. er. . 
2.40 
*Includes also o. 27 F and trace of LLO. 
I. Tavolatal janeirose-appianose [haiiynitic leucite-tephrite]. Osteria di Tavolato, Appian 
Way, Latian District. Washington, analyst. 
II. Tavolatal appianose [haiiynitic leucite-tephrite]. Same locality. Aichino, analyst. Sabatini, 
Mem. Descr. Cart. Geol. Ital., X, 1900, p. 164. 
III. Grano-appianose [foyaite]. J. M. Henry No. 2, near Chamberlain Creek, Magnet Cove, 
Arkansas. Washington, analyst. Jour. Geol., IX, 1901, p. 667. 
IV. Beaveral janeirose [leucite-tinguaite]. Beaver Creek, Bearpaw Mountains, Montana. 
Stokes, analyst. Weed and Pirsson, Am. Jour. Sci., II, 1896, p. 196. 
