512 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
On 1°5 grammes— 

Silica, . : 5 671 
From Alumina, . ‘017 
* 688 = 45 + 866 
Alumina, - : #)) JS LRAS 
Ferrous Oxide, . hy 1-7 ih 
Manganous Oxide, . ; *133 
Lime, : : : © OeShs 
Magnesia, A : . 14°4 
Potash, . P ‘ é “832i 
Soda, : : ; Berge 02 
Water, . F +. 2h 
Carbonic Acid, : . not det. 
97-699 
Impurity, a trace of calcite. 
From Diorite. 
13. From the north-east side of the entrance of Trista Voe, Fetlar, Shetland. 
The mode of occurrence has been noted under anorthite, in the chapter on 
Felspars. ! 
The hornblende is somewhat fibrous-looking, and green on the fresh frac- 
ture ; jet black and highly lustrous on the exposed surfaces. A portion from 
the unaltered green interior was taken. Specific gravity, 3°09. 
1° 3025 grammes yielded— 

Silica, : 4 : . 41°628 
Alumina, . ‘ ; . di 63i 
Ferric Oxide, . : eee hs. 
Ferrous Oxide, : . 8:949 
Manganous Oxide, . : 307 
Lime, é : 5 - | 9° 247 
Magnesia, : : 5 L809 
Potash, . ; , ’ 63 
Soda, ; ; : ES 
Water, . ; . Pb 399 
99 - 368 
Loss in bath, : 423 per cent. 

a 
