MODE XIII. MICA SLATE. 



The same, with v schorl, from the Grampians. 



The same, with sappare, the kyanite of Wer- 

 ner, from the mainland of Shetland, and from 

 Aberdeenshire *. 



The same, with various ores. 



Saussure mentions the following varieties : 



A rock of reddish mica slate, of which the 



r~ 



leaves, being often curved, present at intervals 

 quartz in the form of lentiles, but often some 

 inches in length, and one or two in thickness. 

 1366. 



A remarkable mica slate, composed of thin 

 white and grey leaves, so as to appear on the 

 sides like a striped stuff; the grey part being 

 mica, and the white a very fine arenaceous quartz. 

 1474. 



A gneiss, composed of jad and siderite ; his jad 

 being probably compact felspar. 1331. 



A part of the chain of Mont Blanc consists of a 

 hard ferruginous quartz, mixed with mica. 847. 



* Sappare is the ancient Scotish name, retained by Saussure, who 

 informs us that he first received the substance from the duke of 

 Gordon. Werner's alteration is alike useless and absurd, the ori- 

 ginal appellation implying its similarity to sapphire, for which it, 

 has sometimes been substituted by jewellers. 



