PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 71 
I have said that this yellow quartz is first seen on the hill of Ben Bhrackie ; 
it re-appears with even a red hue on the ridge to the east of the Hill of Tulloch, 
and it may be found here and again—notably on Ben Derag in Glen Lyon, Meall 
Luaidhe, and Meall Ghaordie (Girdy), along the whole ridge as far as the north 
slopes of Fiarach near Crianlarich, and the col between Ben Yoss and Ben 
Laoigh (Loy). 
Parallel to but north of the belt of yellow quartz, there occurs a more 
strongly developed snow-white saccharoid variety; but this is also found 
in quartzose gneiss, as on the east slopes of Carn Aosda and Carn 
Chrionaidh in Glen Clunie, and the south-east slopes of Ben Uran; it is 
not in that rock, however, by any means so strongly developed as in the 
mica slate. 
Of its localities in the latter rock, in none is it so strongly developed as 
in a knoll to the north-east of the summit of Meall Ghaordie; on the south- 
west side of this knoll it forms layers of nearly a foot in thickness, and 
of a purity of colour which was quite equal to the snow out of which I once 
quarried it. 
In a nearly parallel arrangement to the above yellow and white belts, but 
to the south of both, lies the third, which is quite as marked in its peculiar 
features. 
In the most characteristic specimens, such as are found in the gorge of 
the Loch of Chat, between Meall Garabh and Ben Lawers, at the foot of 
the cliffs of Craig Cailleach, and in greatest abundance in the Creag 
Mohr of Glen Lochy, it may be said to present itself as a hyaline colloidal 
cairngorm. 
I purposely use the italicised word to give force to the peculiarity of its 
appearance, which is that of a large mass of gum, being never crystallised, 
and having a more than ordinary vitreous lustre. 
The colour here, in the finest specimens, is somewhat like that of 
the finer varieties of cairngorm, but it is very much more delicate, being 
of a pale brown, markedly dashed with an amethystine tint,—it might be 
almost called a watery claret. 
When cut, it forms stones much to be preferred to any of the brown 
varieties of the cairngorm. 
Now, this variety of quartz, in its finest specimens, carries filaments of 
rutile— Venus’ hair—and chlorite. When degraded somewhat in colour it still 
carries chlorite; and when still further degraded almost to a muddy white, 
when it is still somewhat hyaline, it carries ilmenite. 
The range of this variety may be said to commence on the western slopes 
of Meall Gruaidh (Croy) ; to be chloritic and rutiliferous to near Crianlarich; to 
carry ilmenite from Craig Cailleach, Ben More, and the group around the pic- 
VOL. XXIX. PART I. a 
