MICACEOUS SCHIST. 271 



The texture of micaceous schist is various; 

 being coarse, or fine, according to the magnitude 

 and disposition of the parts of which it is formed. 

 The aspect of the fracture is equally various ; 

 depending, moreover, not only on this cause, but 

 on the direction which it bears towards the 

 laminae of the stone. Thus, in a parallel frac- 

 ture, a smooth surface of mica alone will often 

 appear ; while, in the reverse direction, quartz 

 only, is sometimes visible. 



Whether the texture of micaceous schist is to 

 be considered as crystalline arid granular, or 

 laminar, depends on the particular variety under 

 examination. In many cases, where the mica is 

 not only abundant but continuous, it is strictly 

 laminar. - Where that is abundant, but less .con- 

 tinuous, it is either minutely and imperfectly 

 laminar, or scaly; and where the quartz, on the 

 contrary, predominates, or is irregularly inter- 

 mixed with the mica, it is scaly and granular to- 

 gether, or almost purely granular and crystalline, 

 or continuously crystalline. In all these varieties 

 of texture, it corresponds very nearly with gneiss ; 



