pave BULLETIN CF THE 
syenite type. These analyses were made by Dr. W. H. Melville in the 
laboratory of the United States Geological Survey at Washington. For 
comparison, Analyses I. of Theralite, II. Elzolite-syenite? (“gray 
granite,” Fourche Mountain, Arkansas), and III. Acmite-trachyte ® 
(from the Kiihlsbrunnen Siebengebirge, Germany), are introduced for 
comparison : — 
65. 181. 297. 145. i aT: III. 
SiO, 58.70 62.17 64.33 59.66 43.17 69.70 64.21 
Al,O5 1926 1858 17.52 16.97 1524 1885 16.98 
Fe,0, $37: 215 ©9806. > 818 761 485 6.69 
FeO 058 105 094 1.15 2.67 
MnO 0.10 tr. 0.35 0.19 
CaO (All 57 5 OO 282 10.63 1.34 0.49 
MgO 076 0.73 034 0.80 581 068 0.18 
Na,O S560) “756s. 7308 mae es 568 629 6.18 
K,0 Abe |. 3.88, OS ie ary, ADT, eb On) une taet 
TiO, tr. tr. tr. ir: 
P.O; 0.10 O11 tr. 0.14 
Ig o67 163° “0.05 268 357 188 1.00 
Loss at 105° 007 007) 004° 007 Oot 
100.00 99.50 99.67 99.56 99.39 99.56 99.09 
Comparison with other Acmite-trachytes. — In chemical and mineralogi- 
cal composition and habitus, the fine-grained rocks are almost identical 
with the classical acmite-trachyte from the Kthlsbrunnen in the Sie- 
bengebirge. The microscopic characters of the German rock are given 
in Rosenbusch, (Mik. Physiog., Vol. II. p. 599,) where it is stated that 
the rock, when weathered, is filled with peculiar round pores, which do 
not exist in the fresh rock, but are there represented by areas of a 
brownish yellow isotropic, or partly cryptocrystalline substance, which 
is occasionally developed in radially built spherulites of positive charac- 
ter, a single spherulite occupying the space of a subsequent cavity. In 
slides from a very fresh specimen of the German rock collected by one 
of the writers, the yellowish brown color of these areas is very faint or 
1 J. E. Wolff, Petrography of the Crazy Mountains, 1885. 
2 Williams, loc. cit., p. 81. 
3 G. Bischof, in Von Dechen’s Geogn. Beschr. d. Siebengebirges. Ver. d. Preuss. 
Rh. und West., Bd. IX. p. 340. 
