Editorial Comment. 389 
labradorite, with accessory quartz, andesine, biotite magne- 
tite, pyrite, apatite and zircon. The structure is granulitic to 
granular. 
A quartz dioryte gneiss from an inclusion (1274) is dark 
gray, foliated and banded, in which composite bands alternate 
with light-colored and dark-colored bands. It is composed es- 
sentially of quartz, oligoclase and hornblende, while in certain 
bands biotite is common, and in others microcline occurs. Ac- 
cessorily are found also orthoclase, sphene, ilmenite and ap- 
atite. The structure approaches granitic, the grains partially 
interlocking. "The rock seems in fact to have approached 
very closely, both in structure and in composition, to the gneiss 
which lies near it." 
Making a mechanical separation of the mineral constituents 
of the rock samples studied, the author tabulates them under 
the heads : basic constituents, calcite, scapolite, labradorites, an- 
desite, oligoclase, quartz, microcline and orthoclase. He finds 
by this that the basic minerals are most abundant in the pyrox- 
enytes and the amphiboly tes along the contact zone ; that the 
gray gneisses which are "in patches in the granite," are hardly 
distinguishable from some of the masses that are distinct in- 
clusions ; that the basic inclusions are prevailingly hornblendic 
(amphibolyte) while the contact basic rocks are more fre 
quently augitic (pyroxenyte) ; that both the inclusions and 
the contact rocks contain labradorite; that the inclusions, 
whether basic or acid, contain no scapolite nor calcite, but at 
the contact zone these minerals are both common ; that oligo- 
clase, quartz and microcline are in the foliated granite, the 
gray gneisses and in the quartz-dioryte granite, but that in 
a gray gneiss in which quartz is abundant (51 p. c. ) andesine 
takes the place of oligoclase. 
In making a final inquiry as to the origin of the basic rocks 
at the contact and as to the real nature of the dark streaks and 
patches held by the gneissic granites, the author remarks : 
"The principal materials which must have been added to 
the elements of the limestone to produce the various silicate 
minerals observed in the altered limestones are : silica, alumina, 
iron, magnesia, alkalies, and clorine (for scapolite.) As to the 
source of these materials, there are two possible explanations ; 
either they existed in the limestone or in the beds interstratified 
