1892.] Mineralogy and Petrography. 769 
original microline in the schist is often surrounded by a rim of new 
microline or of albite with the same orientation as the kernel. Arms 
from this extend into the nucleus, until finally the new material has 
entirely replaced the old. In a few notes on some rocks from the 
Lake District, England, Hutchings" mentions briefly the character- 
istics of a biotite-quartz-andesite, and describes a series of hyalopilitic 
andesites, and one rock whose chemical composition is that of trachyte, 
while its mineral components are those of an andesite. He also briefly 
alludes to an augite porphyrite and a granular diabase. Another 
occurrence of peridotite has been discovered in central New York, 
this time as a small dyke in a fault fissure near Manheim, seven miles 
east ot Little Falls. The rock as described by Smyth” consists of 
phenocrysts of biotite and olivine in a groundmass of glass, biotite, 
magnetite, perofskite and a fibrous mineral supposed to be microlitic 
olivine. Among the eruptive rocks of Flag-staff Hill, Boulder Co., 
Col., Palmer” has discovered quartz porphyries with phenocrysts of 
quartz, feldspar and black mica in a decomposed microfelsitic 
base, showing here and there evidences of flow structure. From its 
analysis the rock seems to be an andesite rather than a quartz-por- 
phyry. In a recent bulletin Mr. Diller“ gives a full account of the 
cone of the volcano that erupted the quartz-basalt described by him a 
year or so ago, as well as an excellent discussion of the character of 
its lava. A granitite from Farérolle in the Puy-de-Dém, France, 
contains in addition to its essential constituents fluorite, autunite and 
torbenite.” 
Quartz.—At Pitourees-en-Lordat, France, are beds of dolomitic 
limestone interlaminated with thin beds of tale schist and cut by veins 
` of quartz in which Lacroix” has found some very remarkable twisted 
quartz crystals. Some of these are simply bent in one plane; others 
are now spiral, and each seems to have been affected independently of 
its neighbors. The force that produced the deformation in the shape 
of the crystals also strongly modified their internal structure, so that 
sections parallel to ¢ show little areas differently orienated like the 
grains in a quartzite, while in sections perpendicular to ¢ uniaxial 
UGeol. Magazine, 1891, p. 536. 
, PAmer. Jour. Sci., April, 1892, p. 322. 
13Proc. Col. Sci. Soc., iii, 1889, p. 230, and 1890, p. 351. 
“Bull. U. S. Geol. Survey, No. 79. 
15Gonnard, Bull. Soc. Franç. d. Min., xiv; p: 223. 
Bull, Soc. Franç. d. Min., xiv, 1892, p. 306. 
