Review of Recent Geological Literature. 193 
The contact phenomena of highly alkaline rocks arc of extreme in- 
terest and importance to the petrographer. The introduction of alka- 
lies in all the metamorphosed sediments is made manifest by the abun- 
dance of orthoclase. In certain cases the evidence is still better; in 
one of the samples studied the feldspathic hornstone is separated from 
the sycnyte by a mclanocratic zone in which the pyroxene is no longer 
segirine-augite, but ajgirine, accompanied by small crystals of arfved- 
sonite. Lacroix remarks (p. 216) that: "If one did not find all pos- 
sible gradations between this rock so full of segirine and the hornstone 
(comeennc) of characteristic structure, one would be tempted to com- 
pare it with the ?egirine schists described by Brogger as a varying 
facies of the nepheline syenyte of Grass-Aro." 
In chapter three contact phenomena of highly alkaline granites are 
described. They are characterized especially by the introduction of for- 
eign elements into the Liassic sediments ; the fact that foreign elements 
have been introduced is rendered particularly clear by the nature of 
the minerals developed in the sandstones and modified schists ; besides 
orthoclase^ there are minerals rich in soda, namely, jegirine, riebeckite 
and arfvedsonite, which are not commonly found as the product of 
contact metamorphism. But these alkaline minerals are precisely those 
which characterize the eruptive rock itself, and the pre-existence in 
normal sediments of all the elements necessary for their formation can- 
not be held as probable The author calls attention further to the im- 
portance of his discovery of fluorite as a mineral regularly distributed 
in a metamorphic rock of the region ; the mineral has not heretofore 
been described in this' role; 
In chapter four, which is devoted chiefly to a summary statement, 
it is stated that one of the clearest results of the study is the estab- 
lishment of the identity of the rock family called by the author nepheline 
monzonytes. It is the type intermediate between the nepheline syenytes 
and nepheline gabbros, and is characterized by the association of neph 
eline with alkaline and basic feldspars It is also worthy of note that 
barkevikite seems to be the normal pyroxene of the type. 
Finally, it is worthy of remark that the author has described in 
some detail an unusually large number of rare and unknown minerals, 
such as eudyalite, catapleite, rinkite. and others unnamed. a. n. w. 
MONTHLY AUTHOR'S CATALOGUE 
OF AMERICAN GEOLOGICAL LITERATURE 
ARRANGED ALPHABETICALLY. 
ANON. 
The behavior of the minerals and gems of the Morgan collection 
toward radium and other sources of light. (Am. Mus. Jour., vol. IV, 
Jan.. 1904, p. 3.) 
