= No. 387] REVIEWS OF RECENT LITERATURE. 281 
crysts of plagioclase, augite, and opacitic pseudomorphs of horn- 
blende. The porphyritic plagioclase occupies about half the mass 
-of the rock. Like the feldspar of the groundmass, it is a basic 
labradorite. The rock is thus a hornblende-andesite. 
Dike Rocks of Portland, Me. — Lord' maps and briefly describes 
the basic and acid dikes that cut the schists in Casco Bay and on 
Point Elizabeth, Portland, Me. The basic dikes are néarly all por- 
phyritic. In composition they are olivinitic and enstatitic diabases, 
and camptonites. The acid ones are pegmatites and aplites. The - 
rock called camptonite is composed of porphyritic olivines and augites 
in a groundmass consisting of idiomorphic brown hornblende, anortho- 
clase, magnetite, and secondary products. The hornblende is in 
small prisms, some of which contain remnants of augite, and there- 
fore are believed to be paramorphic. The anorthoclase is in lath- 
shaped crystals arranged radially. Analyses of the anorthoclase (I) 
and the camptonite (IT) follow: 
SiO, TiO, Al,O; FeO, FeO CaO MgO NaO K,O H,O Total 
LPi 20.79 2.88 4.27 16 Bog {iy -21665= 100.36 
Il. 45.20° .68 17.83 5.98 6.55 7.89. 5.29 Aas Sis — 5.53 == 1060.60 
In the course of his work the author separated the hornblende 
from the camptonite of Campton Falls, N. H., and subjected it to 
analysis with this result: 
Si0; TiO, AlO FeO; FeO CaO MgO Nao. KO Total 
37:80 — 4.54 12.89 6.14 12.55 13.64 4.10 5.26 3.24 = 100,16 
_ Notes. — A biotite-tinguaite dike cuts through the augite-syenite 
of Gales rocks, Manchester, Essex County, Mass. According to 
Eakle,? the structure of the rock differs from that of a typical tin- 
guaite in that the feldspar and aegirine are in lath-shaped and pris- 
matic crystals rather than in the acicular forms characteristic of this 
rock. In this respect it resembles solvsbergite. The composition is: 
SiO, TiO, Al,O; Fe,0; FeO MuO CaO MgO K,O Na,O H,Oat 110° H,O Cl Total 
60.05 II 19,097 433 To 79- <9? .23 3.24 7-69 +15 1.26 .28= 100.04 
Oetling® has made a number of experiments to determine the 
effect of various conditions,on the manner of crystallization of rock 
magmas, and has incorporated his results in an article full of inter- 
esting comments on his experimental methods and suggestions for 
future work on the subject. 
1 Amer. Geol., vol. xxii, 
2 Amer. Journ. Sci., a vi C89. p. 489. 
8 Min. u. Petrog. Mitth., Bd. xvii, p. 331. 
