1() / DOMAIN viir COMPOSITE. 



NOME XII. FELSPAR, QUARTZ, TALC. 



This noble rock contains plates of splendid 

 talc, varying in size from half an inch to many 

 feet in diameter. It chiefly occurs in the Ura- 

 lian mountains, whence talc has sometimes been 

 called Muscovy glass. 



NOME XIII. FELSPAR, FIBROUS SIDERITE. 



A rock in confused veins of felspar, white 

 mica, and green fibrous siderite *. 



NOME XIV. FELSPAR, CALCAREOUS SPAR. 



A rock of great rarity, and seldom occurring 

 except in the ejections of Mount Vesuvius, 

 which also affords a composite stone of felspar, 

 garnets, and actinote ; with other aggregations 

 on which it would be tedious to enlarge. Nor 

 is it certain that they occur in such masses as 

 to constitute rocks. Many may be mere para- 

 sites or vein stones. 



* Sauss. 1359. 



