363 
syenite magma. Further evidence is afforded by the fact that 
the syenites of the Ilimausak complex, and at all other places 
where they come into contact with the sandstone, contain con- 
siderable quantities of quartz, while no enrichment in this min- 
eral is ever observed at the junctions with Algonkian granite or 
diabase. 
Under these conditions it is of interest to see whether the 
composition of the hybrid granite agrees with what we might 
expect if it were the result of an addition of sandstone mate- 
rial to augite-syenite. The sandstone has not been chemically 
analyzed, but on microscopic examination the sandstone frag- 
ments in the augite-syenite of Iviangusat have been proved to 
consist of rather pure quartzite, and their structure in consequence 
of the contact metamorphism is crystalline. At other localities 
felspar grains also are found in the sandstone, and with them 
a cementing material which is mainly silica. It has therefore 
been calculated, first, how much pure quartz must be added to 
augite-syenite in order to raise the silica percentage to the 
same value as in the soda-granite; and secondly, how much 
quartz and felspar have to be added to augite-syenite in order 
to produce a mixture which has the same percentages of silica 
and alkalies as the granite. 
Calculated and actual composition of hybrid soda-granite. 
A B С D 
SOS, LC MAUR 70:7 70:7 70:69 
В) sales 1:82 152 "6 "67 
АО Е 15.59 10°6 13:8 13°67 
Fe;0:- 1°61 11 = 129 
ед. 7:62 Sal 2:5 2°81 
MnO .... "14 ‘1 = 15 
MgO.. Al 3 1 trace 
Саб 3773 2-5 1:2 "38 
Na,0.. 7219 5.2 Dis 5:28 
Ky Ona 4°38 2:9 51 5°06 
PDE а. "36 2 >i | 
Total.... 10000 99:9 999 100-00 
