258 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
10. From Glen Beg, Clgnale: 
The exact relationships of the specimens, now to be described, it is not — 
easy to determine, as the block from which they were taken was a loose, though 
not a transported one. . 
It lay, along with a number of masses of primary serpentinous limestone, at 
the foot of a cliff, in the bed of lime which lies about five hundred yards above — 
the hamlet of Balvraid. ~ 
Over the limestone the ground is, in the immediate neighbourhood, so 
covered that its junctions cannot be seen ; backward, in the hill, gneiss is first 
come upon. 
On the side of the stream Seats to see, and further down the glen, 
where the lime curves round the foot of Bieneghapple, an augite rock lies under 
it ; while it is covered by a rock composed of granular augite, dark red garnet, 
a pyrite ;—a compound of wonderful toughness. 
I incline to think that this rock may accompany the lime in its northern 
fold, and that a labradorite belt intervenes, as in so many other localities. 
The. chief portion of the mass of rock mentioned, consisted of a brown, 

granular mineral, which is new—and will be after described under the name of 
balvraidite,—the labradorite under consideration, the blue lustrous orthoclase, 
the analysis of which has been given,—and smaller ag of Biotite: there 
was also some granular calcite. - 
The labradorite occurs in two forms, both of which are peculiar. The first, 
of which there was but little, may be called saccharoid, from its resemblance to 
loaf-sugar ; the second much resembled the Norwegian radiated Cleavelandite, 
in all but the want of divergence in the pseudofibrous structure, that being of 
a parallel disposition in the Balvraid mineral. In both varieties the colour and 
. lustre was that of bleached wax, and both fuse readily, with much fot . 
into a blebby glass. 
The specific gravity of the granular variety was 2:705; 1° bi 08 grammes - 
-yielded— 
Siliea,. | ex we 788 
From Alumina, . , 2 (2 
2 {euIl =n) 47 4a 
Alumina, . : LMide 4 e 28° 023 
Ferric Oxide, : : ; “343 
Magnesia, . : : Cee TS os ed 
Lime, - . ; : ‘ 11, 033 
Potash, , : : 3. OLD 
Soda, : : : rE A; 4-613 
Water, 5 = 202 

100:577 

