82 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
1-3 grammes yielded— 
Silica, ‘ ‘ ‘401 
From Alumina, O15 
*416 = aye 
Alumina," . ; oe vise ss 
Ferric Oxide, . ‘ k Le ey 
Ferrous Oxide, : 2 eee 
Time, 3 : : 1° 569 
Magnesia, . ; . 20°423 
Water, . : : kD aD 
100: 403 
Loses 5°7 per cent of water at 212°; insoluble silica, 5 ° 79 per cent. 
3. From Dumbuck, on the Clyde.—Occurs in imbedded patches up to the 
size of beans, in a somewhat decomposing porphyritic trap, a little north of 
Dumbuck hill. These small masses are frequently irregular in shape, and do 
not seem as if they had filled cavities which had been pre-existent. The rock 
contains in association decomposing augite (Ferrite, of WALLACE Youne), 
olivine, and calcite. 
The Delessite is of a very dark-green colour, but is markedly lighter in hue 
when first exposed; it is very soft, has a minutely-foliated structure, and a 
specific gravity of 2 ° 598. 
1 - 3028 grammes yielded— 
Silica, : 5 * 398 
From Alumina, °019 
“lily = 32° 014 
Alumina, : F 2 eS TA: 
Ferric Oxide, . : s tL 18i 
Ferrous Oxide, , + ph MOCK 
Manganous Oxide, . ‘ trace 
Lime, . ae Pm Os 
Magnesia, : : . 19:64 
Water, . : ; » - do e456 
100 - 644 
Lost 6° 3 of water at 212°; insoluble silica, 8 : 893 per cent. 
4. Occurs in a porphyritic amygdaloid, along with zeolites, at the Long 
Craig, Dumbartonshire. Colour very dark green, structure massive-granular, 
rarely glistening. Specific gravity, 2° 656. 
The first specimen I have from this locality was given to me by the late 
ALEXANDER BRYSON. 
