MODE VII. SAI7SSUEITE. 359 



" 2. Trap Cornfenne*. This variety is hard; 

 it wears iron, but does not sparkle ; it is com- 

 pact ; its grain is consequently fine, close, and 

 absolutely dull. This is what distinguishes trap 

 from basalt; the latter always showing in its 

 fracture a grain rather crystalline. It breaks in 

 parallelepipeds : its fracture is sometimes con- 

 choidal. Its most general colour is black, but 

 there is some, bluish, greenish, and reddish. 

 (Wall.) 



" The trap here mentioned is an homogenous 

 rock. It is easily distinguished by its charac- 

 ters from the trapose rocks. 

 . u This rock is very common in several parts 

 of Sweden. 



<c 3. Lydian Corneenne^. This corn&enne is 

 black, dull, compact ; it is softer than the trap, 

 or cornienne, and has not the parallelopided frac- 

 ture : it is, on the contrary, perfectly compact, 

 and sometimes rather schistose : it is scratched 

 not only by iron, but also by copper, when the 

 angle or edge of a piece of copper is applied; 

 but when this rock is rubbed with the flat or 







" * Corneus trapezius. Wall. Trap is a Swedish word, which 

 means stairs. This name has been giveivto this corneenne, because 

 the mountains which it forms present a kind of steps or seats in 

 their declivities." (Wall.) 



** f Corneus trapezius. Lapis Lydms" (Wall.) 



