on the Newry pitch-stone , &c. 315 
“ to Belfast. Its length, so far as hitherto observed, is half 
“ a mile. 
“ The rock, which is covered with mould to the depth of a 
“ foot, consists of a grey granite. The vein is about two feet 
“ and a half, or two and a quarter in width ; at the places 
“ of contact, both the granite and pitch-stone are disinte- 
“ grated, the latter being almost as soft as clay, but becoming 
“ gradually harder as it approaches the center of the vein. 
“ The structure of the vein is foliated, the folia being per- 
“ pendicular to the horizon, and also to the walls ; and, be- 
“ sides these, there are seams, that run longitudinally, parallel 
“ to the horizon, and nearly perpendicular to the folia. 
“ Although this substance presents some peculiarity, in 
“ being divisible into rhomboidal fragments, it approaches in 
“ this respect to th q pitch- stone of Arran, (in lamellar concre- 
“ tions) which holds as it were a middle place between it, and 
“ that possessing the more usual characters. 
“ Mr. Jameson has described a vein of pitch-stone “ running 
“ in granite” observed by himself in Arran ;* and he states 
“ that lamellar distinct concretions have been hitherto ob- 
“ served in the pitch-stone of that island only.”-f' 
To the geological account of this mineral, above given, I 
have only to add, that the granite which it traverses is rather 
of a soft kind, containing much felspar, and disposed to be 
converted, by decomposition, into lithomarge ; and that a 
vein of basalt nearly parallel to it, at the distance of about an 
hundred yards, passes through the same rock of granite. This 
basalt very readily disintegrates by exposure to air and mois- 
ture ; and it contains spheroidal concentric balls of basalt of 
* Min. of Scottish Isles, 4to. vol. I. p. 81. f Jameson’s Mineralogy, vol. I. p. 261. 
