PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 455 
These ¢ cleavages are evident to the sight by a parallel lineation of the 
mineral: in the more transparent of the Shinness specimens this lineation 
appears as narrow, opaque white bands ; in the sahlites generally, as lines of 
a depth of colour paler than that of the general mass. This lineation con- 
stitutes the most characteristic microscopic feature of the stone. 
2. From granular limestone, about two hundred yards to the south-west of 
Totaig, on Loch Ailsh. 
The malacolite here was rare ; it occurred in imbedded crystalline lumps of 
a somewhat platey structure, and a pale dove-blue colour. The associated 
minerals were, nodular imbedded serpentine of green and blue-black tints, and 
a semi-pseudomorphic substance, afterwards to be noticed under the name of 
Totaigite. Specific gravity, 3° 2. 
On 1°31 grammes— 
Silica, ; 2 - 66 
From Alumina, . - 004 
664 = 50 : 687 
Alumina, . : : : - 029 
Ferric Oxide, . : 3 oa 
Manganous Oxide, . : °068 
itimeN’  : : . 2 T, 
Magnesia, : tS 090 
Potash; . 4 : d *503 
Soda, : : ‘ . 1:°426 
Water, . : Y Be 66 
100 - 122 
Insoluble silica, 2°56 per cent.; possible impurity, lime. 
3. The limestone of Totaig, lying in micaceous gneiss, with a gentle easterly 
dip, is first seen immediately to the east of the pier, thrusting itself into the 
water in a rounded bluff. This much corroded promontory is studded with pro- 
jecting nodules of large size. These consist of a matted agglomeration of 
crystallised malacolite, with crystals sometimes so free as to exhibit fairly well- 
developed forms. The only other substance of interest here is dark augite 
passing into serpentine, the transition being very clearly exhibited. In the 
neighbourhood, a little to the west, an augitic tremolite and an augitic amian- 
thus, coat the exposed layers of the limestone. From the shore of Loch Ailsh 
the limestone strikes across the country in a southerly direction. Passing 
| under the western slopes of the hill of Ben Chourn in cliffy escarpments, it 
| sinks with the falling ground into the greater glen of Glen Elg towards its 
lower third. After rising from its concealment in the detritus of the valley, it 
