PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 39 
dark micaceous patches which so frequently occur in grey granite—called 
neres by the quarrymen. 
These somewhat kindey-shaped masses most frequently show an angularity 
of form,—-they also almost invariably have the dark mica, which is their chief 
constituent, arranged in a laminated manner, parailel to their longer diagonal, 
whatever be the position of that diagonal,—whether horizontal or vertical. 
These facts alone would lead us to regard them as being not concretions in the 
rock, but fragments of gneiss ;—unresolved, if the word is admissible—unre- 
solved or residual fragments of the gneiss, the metamorphosis of the general 
mass of which resulted in the granitic paste which now holds these fragments 
imbedded. 
Till however the actual nature of these “ neres” is placed beyond question, 
any evidence derived from them must be received with caution. 
Examination, to the extent of ascertaining the relative proportions of the 
two oxides of iron in the minute black scales of the rock itself, shows that 
Haughtonite is the mica of the grey granites of Aberdeenshire. 
I have only lately been able to offer analytical evidence as to its second 
mode of occurrence ; namely, as the mica which occasionally replaces horn- 
blende in diorite. . 
Typical diorite has no mica. In perhaps the most important mass of diorite 
in Scotland, that namely which, showing itself first in the north in the vicinity 
of Portsoy, stretches up the country as far as Morven, the character of the 
rock changes repeatedly and even suddenly to a marked extent. 
This diorite, however, which is most simple in its composition in its northern 
portions, I have elsewhere shown to be not typical even there ; for /abradorite 
is there, as it is throughout, the species of felspar characteristic of the rock ; 
indeed, it is the only felspar to be found therein. 
The repeated changes which take place in the rock seem to result from the 
substitution of augite and Haughtonite for hornblende in the first place,—of 
hypersthene for that Haughtonite in the second,—and from the removal of all the 
chief ingredients, except labradorite and Haughtonite, in the third. Marked as 
such changes are, and absolutely dissimilar as are the extremes of such rocks, 
the gradual steps of the transmutation can be detected, leading to the convic- 
tion that all must be regarded as but varieties of one great rock mass. 
Such has been the conclusion of MaccunLocu, of CUNNINGHAME, and of 
Nicox, who unite in laying them down with one colour,—that colour indicating 
an igneous rock of the granitic type. 
Of this, however, there is, as I have pointed out in my paper on horn- 
blende, considerable doubt ; I therein considered the amount of information to 
be derived from the augitic and hornblendic ingredients of the rock, and we 
have now to see what light may be thrown upon it by its mica. The chief 
