PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 113 
Its colour was dark green, its lustre dull, its structure was minutely foliated 
to granular, its particles could be separated from each other by the nail, which 
left a streak paler than the original colour. 
It was readily and totally decomposed by chlorhydric acid, silica alone 
being left. 
Its specific gravity was 2. 442. 
1:3 grammes yielded— 
Silica, . 3 , *488 
From Alumina, . * 004 
* 492 = 37 * 846 
Alumina, . . : 5 ilet py 
Ferric Oxide, . : ra 
Ferrous Oxide, . ‘ - 9005 
Manganous Oxide, .. Y *461 
. Lime, A : 3) ea 2211 
Magnesia, . : : ant Bs 
Potash, 7 : . 38:°334 
Water, 3 ; 5 S Onell 
99-763 
Loses in the bath 8571 of the above water. Before the blowpipe semi- 
fused into a vesicular brown slag. 
This gives in atoms— 
Atoms. 
Silica, . ? S71 846; 2615 22 122, 37°42 
Alumina, . 10 +924 spa i +395 6 4 11°68 
Ferric Oxide, 9-84 123 2 9:06 
Ferrous Oxide, 9°005 25 | 5 10°19 
Lime, . 4°221 uo 5 3 Ae 
Magnesia, 8 + SAE #26 7 93 
Potash, 3° 334 ; at 1 BON 
Water, : NGSts2 9 L792 32 © 32 16°31 
General Formula— 
8 (Fe, Ca, Mg, K,) Sit+3 (Al, Fe.) Si+16 Hy. 
Or Atoms—-- 
Row Rise Siti) H,.16: 
Possibly there might have been some slight admixture of felspar. The 
replacement in the protoxides is confused. 
