of Devonshire and Cornwall. ]37 



of the serpentine, as if they had been destroyed in consequence of 

 the disintegration of the rock, and carried off by the waters. 



In what formation then, ought we to place the serpentine of the 

 Lizard ? does it belong to the older formation of Werner, or to that 

 which is more recent ? the distinctions are in my opinion so vague, 

 that I am almost led to suspect, that the terms are designedly obscure, 

 in order to avoid being more explicit in the definition. Notwithstand- 

 ing that obscurity, I think I can understand so far, as to discover that 

 the characters by which it is endeavoured to distinguish these two 

 formations, are erroneous, or imply a contradiction, and that if they 

 are followed literally, we shall not in the present instance be able to 

 refer the serpentine of the Lizard, either to the one formation or to 

 the other. 



The oldest formation according to Brochant, is found in the vici- 

 nity of gneiss and of mica slate, is mixed with granular limestone,"^ 

 and sometimes this last even predominates. It appears from what 

 Brochant adds respecting the great extent of the newest serpentine 

 formation, that the oldest is of least extent.f Brongniart says, that 

 the oldest formation seldom rises to a very great height, and in 

 noticing the potstones and the beds of iron ore (Fer oxidule) found 

 in the newest formation, he gives us sufficiently to understand that 

 they are not found in the oldest ; he also states, that the newest 

 serpentine occurs in masses or balls, but does not say, whether this 

 is the form in which the oldest is found.t Kirwan says, that 

 although the oldest serpentine is not metalliferous, yet it contains 

 magnetic iron, and veins of copper. § 



* He docs not say whether chemically or raechanioally. 



f Brochant, Traile de Mineralogie, tome ii. p. 577. 



\ Brongniart, Traite Elementaire dc Mineralogie, tome i. p. 487. 



§ Geological Essays, p. 204. 



