
PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 467 
the beds are evidently being changed into serpentine,—even the unchanged beds 
being crossed in all directions by thin veins of serpentine. 
The rock at Craig Buiroch probably is an extension of one or other of these 
beds.* 
From Hyperite. 
14. It is with no little hesitation that I call the rock I have at present 
to notice by the above name. As it differs markedly in outward aspect and 
composition from typical diabase and gabbro alike, I adopt the name applied 
by Maccuttoc# to the rock which it most resembles. 
This rock forms, if not the chief mass, at least that which confers their 
distinctive features upon the three great hills of Halival, Haiskeval, and 
Tralival in Rum. It also forms many others of the unapproachably rough 
uplands of the same island; and it, moreover, passes, if not always by insen- 
sible gradation, at least in an unmistakable manner, into many of the other 
bedded igneous rocks of the island. 
The name to be assigned to this rock may be of little moment ; its precise 
lithological character may not be of much more; but the fixing its true position 
as regards the strata connected with it, and the proper correlation of it with 
those of the adjoining island of Skye, are of very prominent importance. 
As two geologists of repute have referred to it—JAmESON and MaccuLLocu 
—their opinion as to its nature, and evidence as to its relationships, may be 
cited. 
JAMESON, writing in 1813, says that, on ascending the hill of Halival, 
he found “greenstone, associated with basalt, lying upon the top of sand- 
stone,” and that all the higher hills which he saw “were apparently composed 
of trap-formation rocks.” “I observed several pieces of a rock resembling 
Lydian stone which seemed to traverse the greenstone in the form of veins.” 
MAaccuLtocu, writing in 1819, says: “ Immediately incumbent on the sand- 
stone is observed a great body of augite rock, which is nowhere else so con- 
Spicuous and abundant in Scotland. It varies considerably in aspect, being 
sometimes of a small granular texture, and scarcely to be distinguished from 
common greenstone.” 
From an admirable description of the relations of this rock, extended 
through twelve pages of his book, the following statements are gathered : 
“Jt is in a perpetual state of transition into other members of the trap family.” 
“There is an evident transition into basalt.” “It passes into the same syenite 

* I have in the figure, alongside of the rough crystals of this augite, placed for comparison a 
_ figure of the equally rough cleavage crystals of the Paulite (true hypersthene), with which they are 
sometimes associated ; in these the m angle is slightly more accute; 0b is the face of facile cleavage, 
its lustre being bronzy and somewhat purple. There is, at right angles to this, more a fracture than a 
cleavage, a, the colour of which is black. 
