OF EAST LOTHIAN. 



475 



when distinct, to the conchoidal than to the com- 

 mon earthy jasper; the prevalent colour, is a 

 dusky-yellow, with various shades of brown-red, 

 and sometimes black. It is chiefly in those beds 

 of the formation which are intermediate between 

 claystone and porphyry-slate, that I have found 

 these veins to occur ; they are in general nearly 

 vertical ; and as they descend into the lower beds 

 of the formation, I have observed them to ramify 

 very minutely, and to diminish very much in 

 width, — a fact which is of considerable import- 

 ance, and of which I have numerous examples in 

 hand specimens. 



The collection I have made, shews very plainly 

 the transition of this substance into flint, quartz, 

 calcedony, and into splintery-quartz, approaching 

 to hornstone. 



Some specimens from the Garltons, shew a pas- 

 sage into an earthy dull substance, very much ap- 

 proaching to a compact claystone, and even indi- 

 stinct crystals, approaching to the earthy felspar, 

 occasionally occur in them. This observation of 

 transition, I find anticipated by Professor Jameson, 

 in the first volume of his System, wherein he 

 mentions the distinct passage of claystone into 

 common jasper. These jaspers (the geognostical 

 situation of which is now clearly ascertained) 

 are not of much value for ornamental purpo- 

 ses : though they are susceptible of a good po - 



