190 TRANSACTIONS OF THE [aprR. 16, 
bounded crystals which have, besides the ordinary prism, 
pinacoid and pyramid, apparently i-8, and perhaps other faces. 
Magnetite is not common, though occasionally associated 
with the dark silicates. It appears to be in part titaniferous. 
Titanite has been observed in several sections from near the 
edges of the intrusion, in large, sharply defined crystals. 
Monazite 2—In the heavy concentrates from the crushed rock 
were found one or two crystals of a clear yellow color and high 
refractive index, showing an abundance of faces referable to 
orthorhombic or inclined axes. These may be referred to this 
mineral, which Derby has shown to be accessory in many gra- 
nitic rocks. 
Fic. 2, MicrRoPEeRTHITE. 
On crystal of plagioclase in quartz-diorite. Enlarged 25 diam. 
Secondary products.—Epidote is the most noticeable of these. 
It is very faintly pleochroic from colorless to pale yellow and 
occurs accompanied by a smaller proportion of other minerals, 
replacing the plagioclase, or interleaved with biotite or horn- 
blende. When it replaces plagioclase, an odd-looking rock is 
sometimes produced, composed of opaque green and pink crystals 
in a background of glassy quartz, the pink crystals being 
weathered orthoclase. In other cases the original structure is 
almost obliterated by crushing and epidotization, so that the 
rock is scarcely recognizable. 
' Microcline is often seen, and is regarded as being here a sec- 
ondary structure, developed in orthoclase by paramorphic 
roe Rochester Acad. Sci., Vol. I., p. 198: Amer. Journ. Sci., Vol. XLI., 
p. 309. 
