122 



This structure is not limited to masses, but 

 occurs also in veins. 



The foliated structure is the result of a pecu- 

 liar disposition of parts, and occurs in mixed rocks 

 only ; while the former is equally found in the 

 simple. It consists, rather in a tendency to split 

 into parallel laminae, or in an appearance of pa- 

 rallelism in the disposition of the integrant mine- 

 rals, than in the property of actually splitting. 

 But, as it passes into the schistose structure, no 

 positive limit between these two forms can be as- 

 signed. The distinction is nevertheless conve- 

 nient in practice ; and is visible in gneiss, to which 

 the foliated structure is nearly limited. 



In the foliated structure, the splitting, when it 

 takes place, seldom produces a continuous or even 

 lamina. When it does, the structure must gene- 

 rally be considered schistose. 



The lamina is more frequently uneven and ir- 

 regular than smooth, is deficient in parallelism, 

 and is, not unfrequently, curved. 



The foliated is often combined with a very 

 uneven granular structure. 



