40 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
difficulty lies in connection with the question of the whole rock so coloured 
constituting one mass, unless it be admitted that the rock has at different points 
suffered a varying amount of metamorphism. 
The rock where first seen, near the old battery at Portsoy, consists of a grey 
striated labradorite and a grey brown (red by transmitted light) hornblende, 
with extremely rarely a speck of menaccanite. Here the rock is of a very 
coarse grain; it carries occasional veins of labradorite, and in these only is 
Haughtonite here to be seen. As this rock passes to the eastward, the labradoric 
ingredient increases in quantity, the hornblende becomes light green and uralitic, 
and the rock is altogether much finer in structure. This is, however, the only 
change which can be here detected, and an examination of the rock in all its 
relationships, and a consideration of all its appearances, leaves no room for 
doubt that it has a stratified structure, and is here of a metamorphic nature. 
Upon the west side of the Bay of Durn, however, a rock of a somewhat 
similar nature to this appears, the two being separated by bands—well seen at 
the Harbour of Portsoy—which have a minute crystalline and _ perfectly 
schistose structure. 
The evidences as to the rock on the Durn Shore being a metamorphosed, and 
not an intrusive mass, are by no means so clear; and its constituent minerals 
also differ considerably. 
The small amount of felspar here visible is, indeed, the same; but the 
hornblende has given place, apparently entirely, to a mixture of augite and 
hypersthene, both being in minute crystals, with rare and minute occurrences 
of Haughtonite. Now it is the union as laid down in geological maps, of this 
rock with that previously described, which has not been, and, from the covered- 
up state of the country inland, probably cannot be proved; so that here at 
the outset, as regards this locality at least, it cannot be shown that the horn- 
blende is replaced by augite and Haughtonite, for the rock may be intrin- 
sically different—may, in fact, be of the nature of a non-chloritic diabase. 
In the more southerly portions of this last rock, and also to the eastward, a 
gradual increase in the quantity of Haughtonite and disappearance of the 
hypersthene is obvious; and when we get further south, the rock which 
appears to be the continuation of one or other, or perchance of both of the 
above, becomes pervaded with exfiltration veins, in which the Haughtonite 
again gives place to true hypersthene. This is to be seen on the west slopes 
of Craig Buiroch and at Retannach. The occurrence of a labradoric pitchstone 
gives countenance to the view that the rock is here volcanic. 
As a rule, Haughtonite and true hypersthene do not occur in the same 
locality ; the rock on the west side of the Bay of the Durn, and that on the 
north side of Barra hill, however, contain both. Pyrite is a rare accessory at 
the first, pyrite and menaccanite at the second of these localities. 
