1894,] Mineralogy and Petrography. 517 
Vogt? to be cencentrations from the magma that yielded the gabbro 
since the olivine of this rock often contains small percentages of 
nickel and other comparatively rare metals. The principal ore is a 
nickel marcasite with 3—5.5 per cent. Ni. The same author describes 
a nickeliferous pyrite from Beiern, Norway, whose density is 4.6, crys- 
tallization regular and hardness 4. It is not magnetic. 
A peculiar quartz-porphyry consisting of quartz phenocrysts and 
crystals of apatite and an altered mineral sup to be enstatite 
imbedded in a very fine grained weakly doubly refracting groundmass, 
which is water clear in thin section except where bespattered with dust 
inclusions or amorphous iron oxide, is mentioned by Hornung’ as 
probably forming a sheet among the diabases and clay slates near 
Stalberg in the Harz. 
Since many of the Maryland granites enclose fragments of other 
rocks that have suffered contact metamorphism, and since their micro- 
scopic constituents possess the characteristics of substances that have 
i solidified from fusion, while the roek masses are intrusive in other rocks 
Keyes” believes he is justified in regarding them all as eruptive in 
origin, 
Piedmontite from a new American Locality.—The rhyo- 
lites" of the South Mountain region in Pennsylvania and Maryland 
are characterized by their pink or bright red color, which, according ag 
Williams,” is due to the large quantity of piedmontite in them. This 
rare manganese epidote occurs as a constituent in the rock mass, as 
radiating fibres filling veins and as well terminated crystals ones 
in scheelite occupying cavities in the rock. The latter were we 
enough developed to afford material for optical study. The se ea 
of the crystals is parallel to b. Their pleochroism 18 A=y ellow ; Hi 
amethyst; C=carmine. Optically they are identical with piedmonti 
from other localities. An analysis gave (after correcting for quartz) : 
MnO CaO MgO K,O Na,O H,O CuO PbO Totali 
Šio, Al 
2 Al,O, CeO, R,O, FeO; Mn,0, 9 48 .13 .17 =100.05 
22.07 .89 ET 
3.37 152 478 815 228 18.83 .30 
a result indicating that the South Mountain mineral is neei ” : 
composition between allanite, true piedmontite and mangan-ep . 
"Norges Geol. Underség., 1892. 
Min. u. Petrog. Mitth., XIII, p. 373. 
Bull. Geol. Soc. Amer., Vol. IV, p. 299. 
NAMERICAN NATURALIST, March, 1893, p. 273. 
12 Amer. Jour. Sci., 1893, XLVI, p. 50. 
