688 HENRY S. WASHINGTON 
Gibelé obtained from Mr. Butler, and of ome from the top of Costa 
Zichidi. Two by Foerstner are also given, one of the Montagna 
Grande rock and one of a flow at Porto Scauri. 
ANALYSES OF TRACHYTE, GIBELE TYPE 
(GIBELAL NORDMARKOSE) 
| A B Cc D E Aa Ba Ca 
SHO Heat dina eis 63.43 | 63.30 | 65.27 | 61.47 | 61.43 | 1.057'| 1.055 | 1.088 
VN AOR cneia si insavarae 16.31 | 16.38 | 13.50 | 18.09 | 17.51 . 160 - 161 .132 
Lae Oar alglicarara 2.04 2.54 4.40 5.14 5.11 .O13 .o16 .028 
BeQeaepae tas 3.14 2.36 2 5 3.00 2.30 043 .033 035 
Mig Oil ai iie ae ©.78-| ©.84 | ©.55 Teg? || Co kvt 020 .021 or4 
Ca@ ee ees sre I.70 1.62 0.85 3.00 2.45 030 .029 OI5 
INaZOM via euiiae 6.71 6.36 | 5.19 S05 | O.a2 108 . 103 084 
KE O BOR ape 4.31 4.41 4.21 2.83 3.95 046 -047 045 
EE © sees eles 0.18 0.83 1.98 n.d. n.d. cee cae 
FEOF Sais Niele ia 0.26 | 0.10 | ©o.14 | n.d. n.d. sete ees see 
TOs eau I.19 | 0.71 1.09 | n.d. n.d. .O15 . 009 .O14 
TACO palyinicisto.e lbio's 0.06 ass eae oe Gia ale Bs is Beets 
Je OB eleual tie oneracals ©3828 |) ©2390 |) Oouy || | wick n.d. .OOT 002 .oo 
SOR ta Wee 0.05 eke see Bie barter fas a sa Sera 
IN Gal OYnrd a esiasotees 6 O©.Oh || ial, 0.27 | n.d. n.d. .OO1 nas .OOI 
Ba@ aie niente: 0.05 a 
100.45 | 99.75 |100.14 |100.76 | 99.51 
Below Rione Miliac, Montagna Grande. H.S. Washington, analyst. 
Crater of Monte Gibelé. H.S. Washington, analyst. 
Costa Zichidi. H.S. Washington, analyst. 
Montagna Grande. H. Foerstner, analyst. Zeits. Kryst., VIII (1884), 155. 
E. Porto Scauri. H. Foerstner, analyst. Zeits. Kryst., VIII (1884), 164. 
Aa, Ba, Ca, mol numbers: of A, B, C, respectively. 
SOW > 
The first two analyses are typical ones of distinctly sodic 
trachytes, slightly high in silica and with very high TiO,, con- 
sidering the salic characters of the rocks. They are remarkably 
alike and indicate a general uniformity in the flows of the Gibelé 
volcanoes, since A, coming from the foot of the Miliac scarp, must 
be considerably older than that from the Gibelé crater. The 
analysis of the Zichidi rock C resembles them in general features, 
but is higher in silica and ferric oxide and lower in alumina, mag- 
nesia, lime, and soda. Except for the lower soda it shows affinities 
toward the pantelleritic trachytes. 
Foerstner’s analyses cannot be regarded as very satisfactory, 
partly because of the non-determination of water, titanium, and 
This term is used instead of molecular ratios, following Wright and Van Orstrand 
(Jour. Wash. Acad. Sci., III [1913], 233). 
