MODE XIII. MICA SLATE. 123 



Alps rocks in which scales of iron supplied the 

 place of mica. In all events the black mica 

 must belong to the siderous division; while the 

 white mica, which might be called micarel, and 

 sometimes passes into steatite, ought to be classed 

 among the magnesian substances*. 



Mica slate has a further affinity with the si- 

 derous substances, as, like siderite, it frequently 

 contains garnets. It is very metalliferous, many 

 of the mines of Norway and Sweden, and a part 

 of those of Saxony and Hungary, being situated 

 in this rock. 



STRUCTURE I. REGULAR. 



Mica slate of a jet black, with black quartz, 

 from Switzerland. 



Grey mica slate from Scotland, where it abounds 

 in the Grampian Mountains and some of the isles; 

 not to mention innumerable other regions. 



Grey mica slate, used for ovens (Stellstein), 

 from Sweden. Wall. i. 427. 



* Kirwan has called the brownish black mica micarclle, be* 

 cause it contains no magnesia ! Klaproth found in it : 

 0063 argil 

 2Q5 silex 

 675 iron 



1033 



