MODE II. BASALT. JO, 



which last division the basalt or trap of the 

 moderns, and pretended lava of the French mi- 

 neralogists, properly belongs. For the basalt of 

 Agricola, the trap of Wallerius and Werner, a 

 substance abundant in the Faroe isles*, Sweden, 

 Scotland, Ireland, Saxony, Auvergne, Sicily, &c. 

 may also be traced among the Egyptian and 

 other ancient monuments ; and as Pliny informs 

 us that the name of iron-stone was given on 

 account of its colour and hardness, this appel- 

 lation must have been yet more applicable to 

 fine-grained trap than to siderite, which is of a 

 looser grain and softer cohesion. And while the 

 ancient denominations are so indistinct that they 

 have included green fluor, and the fine green 

 granite of Abyssinia, among the emeralds f, it is 

 easily conceivable that the term basalt was ex- 

 tended to two or three distinct rocks, of a colour 

 and hardness approaching to iron : but even the 

 basaltin, or fine-grained basalt of the ancients, is 

 frequently interspersed with minute grains of 

 quartz or felspar; and monuments of what we 

 would strictly call trap or basalt are compara- 

 tively rare. But as it is evident that the basalt 



* In the north of Europe. This spelling distinguishes them 

 from Ferro, one of the Canaries. 



t There seems little doubt that the pillars said to be of emerald 

 :re of this substance. 



C 2 



