PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND, 315 
The large amount of lime in this garnet is peculiar, when we consider the 
nature of its matrix. 
Iron, Manganese—Alumina, Iron Garnet. 
(Fe’Mn)*Si? + (Al,Fe,)?Si® 
Precious Garnet—Manganesious Garnet. 
From Granitic Belis in Micaceous Gneiss, 
9. From the railway cutting at Glen Skiag, west of the Raven’s Rock, 
Strathpeffer, Ross-shire. 
In carrying the railway through one of. the. ridges which run north and 
south in this small glen, a number of huge egg or lens-shaped masses were dis- 
lodged from the rock. These masses showed on their exterior a platey covering 
of glistening greenish mica. Their bulk necessitated their being broken up for 
removal ; their interior was then seen to consist chiefly of quartz, plentifully . 
studded in all directions with large and brilliant plates of mica, and garnets of 
very unusual beauty of colour. 
In addition, there was found, mewn a in much smaller quantity, black and 
green tourmaline, rarely zircon, and still more rarely apatite. 
The lens-shaped masses were connected with one another through the con- 
tinuity of their micaceous coating, forming what may 
be called a nodose vein; the mica alone, however, 
truly constituted the vein—the quartz, with its included 
minerals, assuming the nodose arrangement. Garnets 
of two colours occur in this rock—the more brilliantly 
coloured is probably the finest in Scotland; it is of 
a light red-currant tint. The crystals of this variety 
are never much over an inch in size; the others are 
larger, of duller lustre, almost granular in structure, 
and of a brownish-red tint. Those of a bright currant red are very trans- 
parent, but much flawed; and they sometimes contain layers of white 
quartz arranged in a concentric manner, parallel to the sides of the leucitoidal 
crystals. ae | 
Of the bright red garnet the specific gravity was 4: 125. 
VOL. XXVIII. PART II. ; 4N 

