THE VOLCANOES AND ROCKS OF PANTELLERIA 697 
base are very small crystals of green aegirite-augite and the pleo- 
chroic brown hornblende, the latter being more abundant than 
the former. Both of these mafic minerals form highly irregular 
shreds and anhedra and are seldom if ever prismatically developed, 
nor do they occur in the wreathlike aggregates so characteristic 
of the preceding type. No magnetite is to be seen in any of the 
specimens nor did I see the biotite mentioned by Rosenbusch. 
Chemical composition.—An analysis was made of the comendite 
which forms the lowest, columnar flow at Cuddia Nera, this being 
the freshest and that which best shows the brown hornblende. 
An analysis of a “‘liparite”’ from Cala Porticello by Foerstner is 
also given, but it is very doubtful if it is of the same type as it 
differs much in chemical composition and he gives no description. 
ANALYSES OF COMENDITE, NERA TYPE 
(NERAL GRORUDOSE) 
A B Aa 
Sit Oras, ste lehn cei eae ee ae ea DUD 67.18 I. 204 
NOR Rett: = e0o008 var Q.72 14.18 .096 
IS@50) hla. tt nc beesd Oks eee ee 3.26 4.00 .020 
IP@O)s 6.5 loos of ae eR eee | LROF 2.48 .O15 
MV ile Obert sne agen oe .cos ene = ls 0.29 0.34 .007 
(CaO). s-a:cche wo carce aoe ae eee 0.82 2.78 O14 
INAAO)s S bold oi Geld Sten Dice meaner 4.42 5.89 .O71 
KAO) 5 6 ob Baie a ee ae ee 4.98 4.01 1053 
GLO) a Ie va ee a 1.96 Terie wat tae ret 
FE Oa ects catessdo sins Shiaoms 0.24 TG BP Se) lee ee 
TUOS «obs siete the geese nea eee 0.62 n.d. 008 
TPO} a, oc6:16 ee RSTn oe nee en 0.10 n.d. oor 
INO) eye 8 5FE Cus eae Re ne ROE 0.05 n.d. .OOI 
99.74 TOONSON ib) Meiatae 
A. Lowest flow, Cuddia Nera. H. S. Washington, analyst. 
B. “Liparite,” Cala Porticello. H. Foerstner, analyst. Zeits. Kryst., VIII (1884), 133. 
Aa. Mol number of A. 
This type differs from those described previously in the high 
silica, which is the highest found by me in any rock of the island. 
The predominance of ferric over ferrous oxide may be noted, and 
the small amounts of magnesia and lime. This rock is also the 
only one analyzed by me which shows a greater percentage of 
potash than of soda, though molecularly the latter is present in 
greater quantity. Foerstner’s partial analysis’ is of interest in 
t Boll. Com. Geol. Ital., 1881, p. 535- 
