_ i 
PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 521 
This diorite is probably an extension of the Portsoy beds. It is well seen 
in association with serpentine at Shenwall, on the Blackwater ; and in similar 
association in a line of rugged cliffs which, at a high altitude, divide the upper 
waters of that stream. Though there is no serpentine visible in Glenbucket, 
yet it reappears in the next glen; the diorife of Colquhanny—unquestionably 
the continuation of the present bed —Oeeep ae the normal position to the east 
of, or above the serpentine. 
From Hornblendie Gneiss. 
16. The mass of rock from which I took the specimen now noticed was 
loose. It lay on the shore of the Kyle of Durness. 
It consisted chiefly of a felspar much resembling in appearance a pinkish 
granular marble. Though very unlike ordinary orthoclase, analysis proved this 
to be that substance. Imbedded in this felspar were crystals of half an inch in 
size, of an appearance intermediate between that of hornblende and sallite. 
After an examination of these crystals, I would not be prepared to say to 
which mineral they belong; for although there are appearances of the horn- 
blendic cleavage, still the c cleavage of augite is quite distinct ; so that we 
may here have a physical compound like the Uralite. Sphene of a light brown 
colour is associated in crystals. 
‘During a late visit to Durness, I have, however, been able to find, if not 
the original site of the transported block, at least a locality affording precisely 
similar substances in similar association. 
This is the north-west slope of Ben Spinna, at a height of about 600 feet. 
Several streams cut deeply into the rounded shoulder of the hill, and 
admirably display the strata. These here dip to the north-east at an angle of 
from 20° to 32°. 
Although the rock is clearly a hornblendic gneiss, I am far from satisfied 
that it is the same as the neighbouring rock of Kean na Bin, which has the 
usual W.S.W. dip: I incline to regard this as a fragment overlying the Durness 
lime—a fragment of a rock to be seen to the east of Whitten Head, let down 
by a great fault running N.E. and S.W. a little higher up the hill. The green 
mineral here occurs both of the same appearance as the Durness specimen 
analysed, and also of one more resembling ordinary hornblende. 
The Durness specimen was of a rich green colour, and was somewhat 
harder than usual. 
VOL, XXVIII. PART II. 6T 
