PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 241 
Its cleavage angle is 86° 14’; its specific gravity, 2 636. 
1°017 grammes yielded— 
Silica, . ; : 421625 
From Alumina, . . 004: 
*629 = 61-848 
Alumina, . : £ AE 703 
Ferric Oxide, : ais ake 3 
Oxide of Manganese, . ailisto 
Magnesia, . : 4 0g 
Lime, . : , . 7120 
Potash, : fy 2463 
Soda, . R é 1h i952 
Water, : : : ° 3790 
100 - 293 
Insoluble silica, 1-113 per cent.; possible impurity, quartz. 
From Hornblendic Slate. 
2. The north-west eminence of the serpentinous hills of the Coyle,im Aber- 
deenshire, consists of hornblende rock; very flaggy on its eastern side. <A 
quarry has been here opened for slabs, at the foot of the last heave of the hill; 
in this, and a little to the east of it, in actynolite slate, thin tortuous veins of 
cream-coloured oligoclase occur ; these veins cut the beds. 
The oligoclase is very opaque, with a somewhat greasy lustre, affording 
cleavages somewhat curved, but giving the angle 86° 32’. It is not striated. 
Its specific gravity is 2° 627. 
1-3 grammes yielded— 
Silica, : ‘ Be Scot Ws 
From Alumina, . : pee cal ON es 
8265 =F oaos 
Alumina, . : : . 21°45 
Ferric Oxide, . : je AE aSY/ 
Magnesia, ; : : °23 
Lime, ° . : ; a On OO 
Potash, . : : le OiiS 
Soda, é : : 2 ieee 
Water, . ; : : *438 
100°1 
Insoluble silica, 3°648 ; possible impurity, the matrix. 
VOL. XXVIII. PART I. 3R 
