MICACEOUS SCHIST. 269 



be independent of the bed, and to involve the 

 laminae of which the stratum is formed, without 

 affecting the stratum itself. Many interesting- 

 geological considerations, not admitting of exa- 

 mination in this place, are connected with this 

 subject. 



In all cases, whether straight or contorted, 

 the structure of micaceous schist, like that of 

 gneiss, is foliated, or laminar; and, as in that 

 rock, the laminae are more or less easily sepa- 

 rated, or the rock is more or less easily fissile, 

 according to the proportion and mode of dispo- 

 sition in which the mica enters into the com- 

 pound. Iu some instances, it maybe separated 

 into slates adapted to ceconomical uses ; in 

 others, the laminar fracture is very irregular and 

 imperfect. Such laminae are sometimes straight, 

 like the general structure of the bed ; but, with- 

 out exhibiting actual contortion or flexure, they 

 are often minutely undulated. These undula- 

 tions, like the contortions, are always most sen- 

 sible on the transverse fracture; but that frac- 

 ture can scarcely ever be neatly effected but by 

 the action of gunpowder; as a less degree of 



