DOMAIN I. SIDEROUS. 



The detached crystals of siderite, and what is 

 called Labradore hornblende, or schillerspar, if 

 it be not another substance, are properly topics of 

 gemmology, or lithology, and not of petralogy, 

 as they never occur in the form of rocks. It may 

 be proper to observe, that siderite is called by 

 many French writers schorl en masse, and some- 

 times schorl spathique. 



The real grunstein of the Swedes is a mixture 

 of siderite and mica, sometimes with particles of 

 quartz*. 



Fine grained siderite, with mica, from Upland. 



The same, large grained, with quartz, from 

 Smoland. 



The same, with spots of steatite, from Taxas in 

 Smoland. 



STRUCTURE II. SCHISTOSE SIDERITE. 



This substance, the hornblende slate of the Ger- 

 mans, is often found in gneiss, as already men- 

 tioned; but it is often joined with compact si- 

 derite ; and, with a greater mixture of magnesia, 

 passes into chlorite slate : for between siderite, 

 chlorite, and actinote, there is a near connexion ; 

 whence Saussure argued that chlorite is merely 



* Wall. i. 436. , Whence it appears that it was also called 

 Binda and Jernlinda : the Saxum ferreum of our author. 



