252 R. Pumpelly—Paragenesis of Copper 
a single center. It is along these planes of radiation that the 
change begins. Every possible gradation is observable. The 
more generally it is an amygdule of compact chlorite, ex- 
hibiting in its fracture the same radiating structure as the 
prehnite. 
No. 48. SHELDEN AND CoLumBIAN Location. 1. Prehnite 
which is the general filling of the cavities in the upper part of 
the amygdaloid of this locality. 2. Feldspar, red. It is quite 
an exceptional occurrence in this neighborhood, and it is in- 
timately associated with the prehnite in a manner that makes 
it seem to be pseudomorphous after it. 
Crystals of epidote and of quartz occur on this feldspar, but 
the specimen gives no insight into their relation, as regard age, 
either to each other or to the feldspar as a secondary product. 
. South Pewasic Mine. In this bed a frequent form 
of the rock is a compact amygdaloid, of which 50 or 60 per 
cent of the volume consists of amygdules from the size of a 
i The trix in a specimen 
@. 
contain, 1. Quartz, clear and filling the cavity. 2. 
copper. The chlorite (apparently delessite) appears to displace 
the quartz; in some amygdules it me : 
of the quartz, giving to this a green color; in others nothing 
remains but a cavernous mass 0 i 
well charged with copper; indeed the copper occurs here only 
with this chlorite. 
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preend a to Ay ee thick, much altered and in places changed t0 
