102 ELEMENTARY GEOLOGY 
than that of slate. That is to say, the schist will split 
into layers much less easily and uniformly than the 
slate. According to the minerals present in the schist, 
various names are given, such as mica schist, horn- 
blende schist, etc. All of these are characterized by 
Al 
Fic. 46. 
Two specimens of gneiss. Left hand specimen not so distinctly banded as 
right hand. 
the banding and ease of splitting, which is due to the 
schistose structure arising from the banding of the 
minerals along planes. As in the case of slate, these 
planes are placed at right angles to the pressure, which 
was present during metamorphism. 
