370 The American Geologist. June, 1895 
Augite occurs in two generations, but by far the larger por- 
tion is allotriomorphie. It is not so prominent as the horn- 
blende. Very few well-developed augite phenocrysts appear. 
Such as are present are usually liglit yellow in color and 
generally show slight pleochroi&m. In dike No. 1 the allo- 
triomorphie augite is decomposed to such an extent that only 
the central portions remain at all fresh. A few minute indi- 
viduals of green pyroxene were found closely associated with 
the augite. Plagioclase is not very abundant. In dike No. 2 
its occurrence is rather unique. It is not uniformly distrib- 
uted through the rock, but is apparently developed in tufts or 
aggregations of individuals. Such an arrangement presents a 
patch-like appearance in the thin sections and in the hand- 
specimens resembles porphj'^ritic structure. Some of these 
white inclusions were found to be pockets of calcite. The 
fresh plagioclase contains exceedingly minute acicular inclu- 
sions, many of which seem to be arranged in parallel series. 
They are regarded as apatite. The plagioclase has also suf- 
fered considerable mechanical deformation. Many of the 
larger individuals are bent and twisted to such an extent in 
some cases as to cause fracture. The groundmass consists of 
an opaque gray substance, resembling decomposed feldspar 
very closely. Considerable glass was found in the interstices 
of the feldspathic portion of the various sections. Compar- 
ing this rock with the original camptonite of Hawes, it should 
be said that the colored bisilicates form a larger portion and 
the feldspar a correspondingly smaller portion of the rock- 
mass than noted in sections of the type rock. 
In conclusion, then, it should be added, that while these dikes 
are legitimately regarded as camptonites they are somewhat 
abnormal in the development of the individual constituents, 
there being but one generation of hornblende and exceedingly 
few augite phenocrysts, fully nine-tenths of the pyroxene be- 
ing allotriomorphie. 
This is but one of a number of occurrences of camptonite 
dikes discovered within the last few years in New England 
and other states. They were first noted by J. W. Hawes* at 
*J. W. Hawes: On a jfroup of dissimilar eruptive rocks from Camp- 
ton, N. H. Am. Jour. Sci., S, vol. xvii, p. 14, 187!). 
