198 NATURE STUDY 



mica; but the mica is more abundant than in granite, 

 and is, in the typical gneiss, arranged in layers. Because 

 of this layering, gneiss is not nearly so valuable a build- 

 ing stone, since it tends to break and to disintegrate 

 along the line of the soft mineral. 



Method : 



The probabilities are that long before you are ready 

 to teach gneiss, the children will have brought in speci- 

 mens. The freshly broken specimens are pretty enough 

 to attract them ; and in city streets, where building of 

 any sort is going on, large heaps of gneiss are to be 

 found. 



In what respect is this stone like granite ? How 

 different ? Is it as good a building stone as granite ? 

 Why not ? Does it make soil ? How ? What does this 

 soil look like ? 



Mica Schist. 

 Facts : 



The origin of mica schist is wrapped in the same 

 obscurity that surrounds that of gneiss. 



It differs from gneiss in the presence of a much greater 

 quantity of mica, occurring in larger pieces and in wider 

 layers. Quartz may be present, or feldspar, or both. It 

 is very apt to contain other minerals, such as garnets. 



Because of the abundance and the arrangement of the 

 mica, it has small value as a building stone. 



Method : 



Specimens of mica schist are almost as easily found as 

 those of gneiss. 



In what respects is this stone like granite ? How 



