* i -~ a _ — a 
———— 
PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 531 
With Gradual Removal of the Silica. 
26. That mineral which was noticed by JAMESON as occurring in Glen 
Urquhart, and called by him anthophyllite, is an excellent illustration of the 
commencement of this,—the next stage in the process. 
The mineral is that termed hydrous anthophyllite, and was probably origi- 
nally an asbestiform tremolite. It occurs in very beautiful fibrous specimens, 
which constitute veins in a very singular if not unique rock. 
It is an excellent illustration of the distinction which should be drawn 
between an altered rock, or alteration product, and a decomposed rock, or 
weathered mineral. There is certainly here no decomposition, no degradation. 
The substance is perfectly fresh, unrotted, and probably more beautiful in its 
silky lustre and specific integrity than was the asbestus from which it pro- 
bably originated. 
This rock is composed almost solely of large crystals of green zoizite and 
plates of Biotite ; very rarely a plate of chlorite is seen; still more rarely 
nodules of chondrodite occur. Its veins carry Wollastonite of a skim-milk 
colour and fibrous structure. 
The fibres of both this and the hydrous anthophyllite run transverse to the 
vein. 
The fibres of the anthophyllite are 4 to 5 inches in length, of a greenish- 
brown colour, a silky lustre, and great toughness. 
The locality is east of the Free Church of Milltown, near the serpentine. 
Specific gravity, 2 ° 811. 
1: 251 gramnies afforded— 

Silica, F : * 586 
From Alumina, . =@11 
OO = AT +721 
Alumina, . d E351926 3° 837 
Ferric Oxide, . : ae -176 
Ferrous Oxide, . an des GLO 5° TAL 
Manganous Oxide, . sae ‘159 
Lime, F ‘ : aa 5° 64 
Magnesia, . : . ae 28° '745 
Potash, : : : Bes - 186 
Soda, . : i cae * 264 
Water, P : ; By 7-648 
HOO? 17 
| 
Insoluble silica, 4° 187 per cent.; was quite pure. 
