166 
of the grain is invariablv much greater than in the common 
variety of the rock: the egirine-prisms attain a length of 5 or 
10 millimeters and a thickness of 2 or 3 millimeters. But such 
more or less massive varieties are of rare occurrence and are 
always very subordinate: the ordinary ægirine-lujavrite of the 
Ilimausak batholite is a rather uniformly fine-grained and 
schistose rock. That the schistosity has not been superim- 
Fig. 17. Ægirine-lujavrite, >< 20. 
Showing felspar (f), eudialyte (e), and nepheline (n), imbedded in a felt-like aggregate of 
æyirine-needles. The white areas surrounding the nepheline are analcime; the black area 
on the right is a portion of a poikilitic anhedron of arfvedsonite. The felspars are mi- 
crocline and albite in separate crystals. 
posed upon the lujavrite by mechanical movements after the 
consolidation, is shown by the large arfvedsonite-anhedra being 
entirely uninfluenced and the schistose structure, therefore, 
is essentially a flow-structure produced by fluxional move- 
ments operating during the earlier stages of the consolidation- 
process but ceasing before the rock had entirely solidified. 
The question connected with the origin of this structure 
will be considered more fully in the last chapter of this 
report. 
