PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 255 
ing giant crystals of hornblende ; the other, some dozen feet apart, has crystals 
of augite of large size replacing the hornblende. 
In both cases the labradorite is massive or impalpable granular—a crypto- 
crystalline or felsitic variety ; where associated with hornblende, it is, in the 
interior, of a pale lavender-blue colour, shading off to white on the exterior,— 
perhaps from weathering. The variety associated with the augite is always 
white. The blue had a specific gravity of 2: 95. 
25 grains yielded— 
Silica, ; ; 3 « 52° 212 

Alumina, . : : . 29°64 
Ferric Oxide, . é 5 ‘48 
Magnesia, . : ; : *263 
Lime, 6 , : . 12° 428 
Potash, . ‘ ; *443 
Soda, - 3 : 2 io G98 
, 1 Water, F : ; i Lid 
99 - 575 
3°86 per cent. of the silica were insoluble; possible impurity unknown. 
Rotu’s law, above referred to, is here Guan ets borne out. 
6. That with the augite had a specific Ce of 2: 954. 
25 grains yielded— 
Silica, : : ; 5) Gor too 
Alumina, . : 3 woo O92 
Ferric Oxide, . Bengt 248 — 
Magnesia, ; . ° 208 
Lime, ah Slits ; - 12-296 
orash Maclean AT 
Soda, : ; : ante 
Water, . J ; ; tout 

100 - 422 
Indissoluble silica, 1- 64 per cent.; possible impurity unknown. 
7. The rock which is found in the diabase of the cliffs immediately to the 
west of the battery at Portsoy, consists almost solely of crystals of labradorite 
imbedded in a confusedly crystalline mass of augite; Biotite, and iserine in 
specks rarely occur. In cavities—which are very rare in such a rock—the 
labradorite is occasionally met with regularly crystallised ; and, throughout, it 
impresses its form upon the augite; but by the action of the sea the labra_ 

