314 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
line. The crystals, said to be from Knock, are of large size, and exhibit the 
interesting oscillation of faces shown in figure. They are of a port-wine 
colour, and their specific gravity is 4°116. 
1:237 grammes yielded— 
Silica, ; ? 3 °44 
From Alumina, . eo SOG 
"459 == 37-105 
Alumina, : -/ 4 | 14°899 
Ferric Oxide, ; ‘ . AGet25 
Ferrous Oxide, . ; . 02°409 
Manganous Oxide, E i 20e 
Lime, : - . : Zag 
Magnesia, 2° 934 
100° 854 
Insoluble silica, 6°57 per cent.; no visible impurity. 
Iron—Alumina, Iron Garnet. 
(Fe’)’Si? + (Al,Fe,)°Si*. 
Almandite. 
From Micaceous Gneiss. 
8. Is found, somewhat rarely, in the quartzose belts of the rocky bluff 
named Clach an Edin, between the mouths of the Navir and the Borgie, in 
Sutherland. 
The colour is brown red; the associated minerals are Haughtonite, ilmenite, 
chlorite, and rutile. 
1:3 grammes yielded— 
Silica, E ; : a oes 
From Alumina, . F . 7016 
Hise = oo 24 
Alumina, . ; : Suse (Us) 
Ferric Oxide, . ; |. tSp69 
Ferrous Oxide, ; . 13°294 
Manganous Oxide, ore 
Limes 4 : :  eretaZ, 
Magnesia, 3° 307 
100°154 
Insoluble silica, 2°509 ; possible impurity, quartz. 

