18 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
Silica, ; P : 634 
From Alumina, . ; *026 
* 660 = 39 +803 
Alumina, ; ; : 14-185 
Ferric Oxide, : 2°594 
Ferrous Oxide, 11-373, 11°748, 11°578 
Manganous Oxide, 24 
Lime, . ; : : : PUNE 
Magnesia, . : ‘ : : 18°32 
Potash, . : : ; ; ‘ 8°43 
Soda, 4 : : : et ibil 
Fluorine, : : s . . *56 
Water, . Dron, 
100° 437 
7°905 per cent. of the silica were insoluble; possible impurity unknown. 
The larger than normal quantity of soda was, doubtless, due to marine submer- 
gence. In the larger quantity of ferric oxide which replaces alumina this 
Biotite differs from the others. 
From Edenitic Rock. 
6. At a turn of the road a little south-east of the Free Church of Milltown, 
Glen Urquhart, the serpentine appears at the surface, and here there is a 
small quantity of a very peculiar rock. 
This is composed of large pale-green crystals of edenite, of the form of 
actynolite ; these are bedded in a mass of plicated crystals of what has more 
resemblance to talc than to Biotite ; their usual colours being a very pale green, 
little removed from white, and they are devoid of elasticity. As accessories, 
there occur thick veins of hydrous-anthophyllite, thinner ones of fibrous 
Wollastonite, garnet with imbedded zircons, and crystalline granules of a new 
mineral resembling chondrodite in appearance. This talc-like Biotite is 
unusually soft, softer indeed than the nail; its specific gravity is 2°781 : occasion- 
ally it passes into flat and elastic plates of a rich brown colour, and high lustre. 
The pale-coloured yielded on 1:3 grammes— 
Silica, 5 : ; “yt 
From Alumina, A °005 
iy et ANTS 20h 
Alumina, ‘ : _ 12°582 
Ferric Oxide, . ; . 1°809 
Ferrous Oxide, . a OMOOD 
Manganous Oxide, 384 
Lime, : f , we Beil 
Magnesia, . ‘ ; + pale 
Potash, ‘ ’ : > 16> Soi: 
Soda, ; ; ; : °953 
Water, : ; ; Oo as 
