NOME I. COMPACT LAVA. 313 



NOME I. COMPACT LAVA. 



The volcanic substances are of such various 

 kinds, that their arrangement becomes more 

 difficult. By far the most important substance 

 is the lava, which must be considered chiefly as 

 it is compact or porous, the former requiring 

 particular attention. In Karsten's catalogue 

 there are only two bits of lava; and as Buffon 

 had prejudices against certain rocks which con- 

 tradicted his system, so Werner seems absolutely 

 to shut his eyes upon the grandeur and import- 

 ance of volcanic productions. Hence they are 

 treated with great neglect, and may be said to 

 be excluded from German cabinets ; while, to 

 the impartial observer, they convey sublime ideas 

 of the wonderful power of nature. 



As the opinion that basaltin is at least some- Basaitm. 

 times volcanic, appears to gain ground, it must, 

 when identified by its geognosy, be admitted as 

 the most compact of all lavas. Like porous 

 lava, it very often contains grains, or even no- 

 dules, of olivine, or what has been called chry- 

 solite; and zeolite forms likewise a common 

 parasitic substance. Neither of these, it would 

 appear, is found in siderite, or in the basalt of the 



