58 THE TRAP FORMATION OF 



j^o. 16. — Has a paste of a blueish grey colour, and appears almost 

 completely saturated with calcareous spar; though much softer than any 

 of those previously mentioned, it possesses greater induration than Nos. 

 17 and 18. 



]\^o. 19.— Is an amygdaloidal mass, consisting of innumerable pea- 

 form nodules of calcareous spar, cemented together by a thin cement of 

 basaltic or wacke clay of a light colour. 



No. 20. — Is fully engrossed by minute crystals of zeolite, excluding 

 from the paste any other mineral. 



, No other trap rocks, than those I have mentioned, are here of obvious 

 and constant occurrence, at least if any other varieties exist I saw them 

 not. — With regard to the simple minerals contained, calcareous spar is the 

 most abundant, green earth, chalcedony, and quartz, are also very preva- 

 lent, but the zeolite minerals may be quoted as scarce. Well defined 

 jasper is rarely seen, but something above an indulated clay, what may be 

 termed semi-formed jasper, is of constant occurrence, so is hornstone ; and 

 both these last are to be foun'd independant, but they are more generally 

 lying contiguous to the limestone from which they are derived. The 

 iron clay so easy to be met with every where, would hardly ever satisfy 

 the mineralogist, for it is for the most part amygdaloidal, and not a simple 

 mineral. It sometimes rises to the rank of a poor earthy red ore, and it 

 is as such worked near Barseah, near Raisen, and at the source of the 

 JDasaon, &c. Olivine throughout is every common, — but I have never 

 procured either a crystal of hornblende or of augite. 



But to the trap, not to the sandstone, belongs a hard white earthy 

 limestone, harsh and gritty to the feel on the fresh fracture, and in which, 



rather 



