1894.] Petrography. 801 
sak* and declared by Kemp’ to be an aggregate of pyroxene, biotite 
and analcite has been examined at another place by the last named 
geologist. It has been found by him to contain leucite. Hussak’s 
determination is thus confirmed. The rock is a leucite tephrite. 
A spherical granite from a boulder discovered on Qonochontogue 
Beach in Southwestern Rhode Island is described by Kemp’ as a 
eoarse granitite, with nodules from two to three inches in diameter 
scattered through it. These consist of a center of coarse plagioclase 
with a little quartz, surrounded by a concentric zone of biotite and 
magnetite, and a peripheral one of radiating plagioclase, whose laths 
end sharply against the granite matrix. The author explains the nod- 
ules as centers of crystallization. 
The rocks that have for the past few years been called muscovadite 
by the Minnesota Geological Survey have recently been examined by 
Grant," who finds among them several distinct rock types. Some of 
muscovadites are fine grained aggregates of pyroxene, quartz and 
feldspar, containing in their midst large flakes of biotite. Others are 
composed of quartz and biotite, etc. These are considered as contact 
rocks. A second class of the muscovadite comprises granulitic gab. 
bros and norites. 
The siliceous oolite of State College, Pa., is composed of radial 
spherules of fibrous chaleedony forming bands around fragments and 
rounded grains of quartz. Between the spherules are bundles of 
chalcedony fibres placed normal to the surface of the spherules nearest 
them, and intermingled with these are granular chalcedony and quartz. 
An oolite from the Tertiary beds of New Jersey is an aggregate of 
sphero-crystals of chalcedony, usually without nuclei. Occasionally 
a cone of fine grained quartz is to be seen, but thisis rare. The 
matrix between the spherules is partly chalcedony and partly quartz.” 
Dupare and Mrazec" refer very briefly to the mineralogical compo- 
sition of an occurrence of Serpentine at Geisspfad in the Swiss Alps. 
The rock now contains hornblende, chromiferous diopside, diallage and 
some secondary substances in addition to serpentine. The rock was 
probably originally'a Lherzolite. 
*Amer. Naturalist, 1893, p. 27 
Tb. 1893, p. 563. 
*Amer. Jour. Sci, XLVII, 1894, p. 333. 
"Trans. N. Y. Acad. Sci., XIII, 1894, p. 140. 
1'21st Ann. Rep. Minn. Survey, p. 147. 
NE. O. Hovey: Bull. Geol. Soc. page Vol. 5, p. 627. 
"Bull. Soc. Frane d. Min., XVI, p. 2 
