1897,] Petrography. 219 
General Notes. 
PETROGRA PHY.’ 
Augen-Gneiss and Intrusive Rocks at Bedford, N. Y.— 
Luquer and Riess’ mention an augen-gneiss near Bedford, West Ches- 
ter Co., N. Y., as covering an area of 15 square miles. The augen are 
in large part orthoclase or microclinic erystals that have been squeezed 
and flattened. They often occur in bands and are always elongated 
parallel to the foliation of the gneiss in which they lie. The rock shows 
abundant evidence of mashing, the large orthoclase constituting the 
augen being bent and the quartz grains associated with them being 
much granulated. The origin of the gneiss is ascribed to the dynamic 
metamorphism of an acid igneousrock. Diorite dykes and great veins 
and masses of pegmatite occur in the gneiss. The pegmatites are re- 
garded as vein masses produced by segregation agencies. 
The Basic End-member of the Augite-Syenite-Nephe- 
line-Syenite Series.—In the Lujavr-Urt on the peninsula of Kola, 
Russia, occurs the feldspar free nepheline-pyroxene rock to which the 
name iolite has been given. Associated with it is an orthoclase bear- 
ing rock whose chemical composition is similar to that of the nepheline 
porphyry from Magnet Cave, Ark., and from Beemerville, N. Y., 
(sussexit of Brégger) and of borolanite from Borolan. An analysis of 
the supposed iolite shows it to differ from typical iolite in possessing 
only aegirine among its bisilicate components, and to be much poorer 
in CaO than the typical rock. The composition of iolite from Tiwaara 
is given in (I), while that of the Lujavr-Urt rock is shown in (ID). 
he composition of the basic end-member of the quartz-augite-syenite 
nepheline-syenite series as calculated by Brogger is shown in (III). 
The author admits that the Lujavr-Urt rock may be regarded as an 
TiO, SiO, AlO; Fes FeO MnO CaO MgO K,0 NaO P,0, H,0 Total 
i. 1.70 42.79 19.89 4,39 2.93 .41 11.76 1.87 1.67 931 1.70 9 = 98.81 
(IT). 45.43 28.77 3.10 .40 1.86 .22 3.38 16.16 99.32 
(TIT). 45. 25. 6.5 ge Je 10 12. 1.00 = 100.00 
aegerine iolite, but he prefers to give it the distinctive name urtite. It 
is defined as a light colored, median grained rock composed of black 
1 Edited by Dr. W. S. Bayley, Colby University, Waterville, Me. 
* Amer. Geologist, XVIII, p. 239. 
