358 DOMAIN IV. TALCOUS. 



possesses sufficient tenacity not to be scratched 

 by the copper knife, which, on the contrary, 

 leaves its mark. It is even difficult sometimes 

 to be scratched with iron. 



" Corneenne is easily melted into a black 

 bright amel, and this character distinguishes it 

 from schistus, when it possesses the texture of it, 

 and from schistose jasper, when it approaches it 

 by its hardness : it almost always acts upon the 

 magnetic needle. 



" Most mineralogists look upon this rock as 

 an intimate and invisible mixture of amphibole* 

 and clay. 



cc We shall establish the following varieties in 

 this species : 



<c 1. Compact Corneenne. It is solid, com- 

 pact, difficult to break ; its fracture is uneven, 

 passing to the conchoidal. 



" I will give, as an example of this variety, 

 the brown paste, approaching to the violet, of 

 the amygdaloids of Drac. Dolomieu considered 

 it as a corneenne well characterised. The paste 

 of the amygdaloids of Derbyshire, called toad- 

 stone, should be equally placed with it, and that 

 of the agates of Oberstein, &c. 



* An absurd name for hornblende or siderite, signifying forsooth 

 emliguous, while there is no substance less ambiguous. P. 



