1895.] Petrography. 473 
In some of the dykes the structure is ophitic, and in others, panidio- 
morphic. If the author’s view as to the origin of the analcite is cor- 
rect, these rocks are clearly related to teschnites. 
A Quartz-Keratophyre from Wisconsin.— Weidman’ has in- 
vestigated the porphyritic rock overlying the Baraboo quartzites of 
Wisconsin, and has shown it to be a quartz-keratophyre. It shows all 
the features of a lava, and is associated with tuffs and a sericite schist. 
The schist is at the contact of the keratophyre with the quartzite, and 
is evidently a result of shearing of the eruptive, The latter is porphy- 
ritic, with plagioclase and anorthoclase phenocrysts (often fractured by 
movements of the lava), and a few partially dissolved quartz pheno- 
crysts in a fine-grained holocrystalline groundmass of quartz and feld- 
spar, which, in addition to the phenocrysts mentioned, contains imbed- 
ded in it ilmenite, biotite and zircon. Many specimens show a flux- 
ion structure and some are spherulitic—the spherules being sometimes 
secondary and sometimes primary bodies. An analysis of a sample of 
the rock gave: 
SiO, ALO, FeO CaO KO NaO H,O S0, Total 
73.00 15.61 195 .79 88 495 1.06 .76= 99.00 
The series of bulletins, of which the author’s article forms the sec- 
ond number, is well printed and is apparently well edited. It is a 
valued addition to the list of science bulletins now being published by 
American colleges. 
Notes.—The crystalline limestones of Warren Co., N. J., contain a 
large number of accessory minerals, which are described by Westgate.* 
It contains irregular masses or concretions of pyroxene, hornblende, 
magnetite and biotite. Quartz, tourmaline, apatite, graphite and gar- 
net are also present in it. The quartz and pyroxene are so abundant 
that, in some cases, they constitute rock-bodies, composed of interlock- 
ing grains of their principal constituents, with a small admixture of 
some others. 
The nickeliferous pyrrohotite of the Gap Mine, Lancaster, Pa., forms 
a peripheral zone around the eastern end of an amphibolite lens, 
which, according to Kemp,’ is an altered norite or peridotite. The ore 
is irregularly intermingled with the hornblende of the amphibolite, 
1 Bull. Univ. Wis. Science Ser., Diy I, p. 35. 
8 Amer. Geologist, Vol. xiv, p. 30 
®Trans. Amer. Inst. Min. Engin. a: 1894. 
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