PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 257 
This labradorite is in somewhat large crystals; of a cream colour, striated, 
brittle, and with a specific gravity of 2°674. It yielded— 

Silica, %. js ; : Hilo 20: 
Alumina, . , é 26.756 
Ferric Oxide, ; ; 1: 818 
Manganous Oxide, i 76 
Magnesia, .  . é *41 
Lime, . : : é IO el 
Potash, : Dalat 
Soda Stee ; j 6°43 
Water, , ‘ : * 684 
100-417. 
From Porphyrite. 
. 9. One of the felsitic intrusive traps, which occur so persistently among the 
_ old red conglomerates of Kincardineshire, shows a cliffy escarpment at a turn 
of the road from Bervie to Catterline, just where the branch road to the church 
of Kinneff diverges. This spot is interesting from the trap being at one and 
the same place highly prophyritic in structure, as well as markedly amygda- 
loidal. ; | 
The imbedded crystals are large flat twins of labradorite. The drusy cavities, 
which are of considerable size, though not numerous, contain large sheafs of red 
‘stilbite, and finely developed crystals of Heulandite, both of a vermilion tint,—- 
radiated quartz,—pale green fibrous, and massive chocolate-coloured saponite. 
The labradorite is colourless to brownish-grey, translucent, and vitreous, but 
weathers dull and white; much flawed, and not striated. . 
1:301 grammes yielded— 
Silica, " 672 
From Alumina, *02 
692 =» 53-189 
Mnming,  ¢. ety. : 26° 431 
Ferric oxide, 3 : 2° 854 
Manganous oxide, _—. tr. 
Magnesia, : : é +922 
Lime, 3 i c 9 - 684 
Potash, . , j Pee 
Soda, . : ; : . 4°594 
H,0, : : 2 726 

SS) SBE 
Insoluble silica, 2°167 per cent.; impurity doubtless a trace of the matrix. 
VOL, XXVIII. PART I. 3X 

