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phenoerysts, which are present in almost as large quantities as 
the ground mass, consist of a white or greenish felspar. They 
have a shape giving broad rectangular sections, their length is 
most frequently about one centimeter, but in some parts of the 
dyke they may attain five centimeters. On microscopic exami- 
nation they appear to a large extent converted into a muscovite- 
like aggregate, whilst the still fresh parts consist of labradorite. 
The ground mass is greenish-gray and fine-grained, the size of 
grain averages 01—03 millimeter. It is made up of orthoclase 
and plagioclase with some augite, iron ore, apatite, and 
chlorite. In symmetrical sections the plagioclase shows extinc- 
tion angles indicating a rather acid labradorite. The augite is 
light gray and is sometimes surrounded by a marginal zone of 
a green colour. The chlorite appears to replace biotite. As 
the rock is rather disintegrated and no chemical analysis has 
been made, it is difficult to say whether it is an essexite-por- 
phyry or a monzonite-porphyry, but when we consider the 
large quantities of orthoclase in the ground mass, the latter 
supposition seems to be the more probable one. 
Another dyke which most likely is also a monzonite-por- 
phyry occurs at a short distance east of the Igaliko settlement. 
This dyke is about 10 meters wide, and strikes almost E.N.E. 
—W.S.W. It has numerous white felspar phenocrysts about 
one centimeter long, and of a shape giving broad rectangular 
sections. They are tolerably fresh, and consist of andesine 
with a rather thin marginal zone of orthoclase. Olivine is 
sometimes to be found in grains of a size of 1 or 2 millimeters. 
The ground mass is almost dense, and of a dark brownish- 
gray colour. It is essentially made up of short felspar laths 
partly orthoclase partly oligoclase, the former most frequently 
as a thick mantle round the latter. The ferromagnesian con- 
stituents are light grayish augite, brownish-green biotite, a little 
olivine, and iron ore. A small quantity of sodalite or analcime 
occurs in the interstices between the felspar laths. A similar 
