THE ISLE OF EIGG. 151 



the two first are met with in all stages between an amor- 

 phous state and a regular columnar arrangement, affording 

 not unfrequently examples of the globular concretionary 

 disposition. Like the trap-rocks of the other western 

 islands, those of Eigg contain several simple minerals : 

 fibrous amethyst, cubicite, calcareous spar, mesole, meso- 

 type, and stilbite occur, lining drusy cavities, some points 

 presenting specimens of the latter little inferior in beauty 

 to the well-known masses of Iceland and Feroe. Small 

 groups of quartz-crystals, associated with stalactitic and 

 botryoidal calcedony, are also abundant in the amygdaloid. 

 When noticing the simple minerals of Eigg, it may here 

 be remarked, that, though the contrary has been stated by 

 Dr MacCulloch, calcedonic veins traverse the columnar 

 porphyry of the Scuir ; these, when a few inches broad, 

 containing cavities lined with crystals of quartz. 



The only other rocks which require notice are those ex- 

 amples of pitchstone and pitchstone-porphyry, which so emi- 

 nently distinguish Eigg from the other Hebrides. Three in- 

 stances of this rock have been described by Professor Jame- 

 son as occurring in Eigg, viz. two veins which traverse the 

 basalt on the southern shore of the island, not very far from 

 the well-known Maclean's Cave; and the pitchstone-por- 

 phyry which rises into the singularly-shaped rock of the 

 Scuir, and which runs across the island as an immense dyke, 

 having a NW. and SE. direction. The pitchstone veins are 

 separated from each other by a distance of about twelve feet, 

 and do not appear to exceed three feet, or three feet and a 

 half in breadth. Both traverse vertically a dark blackish-blue 

 basalt, and, though preserving a general parallelism to each 

 other, exhibit a few slight bendings in their course. They 

 are, in the central parts, of a dark olive-green colour, and 

 pass, as they approach the basalt, into a blue pitchstone, 



