PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 15 
BIOTITE. 
From Granular Limestone. 
1. The limestone, which is the near associate of the serpentine of Polmally, 
in Glen Urquhart, appears in greatest amount, at a height of 700 feet, in the 
hill above Milltown. The somewhat schistose gneiss, which here carries the 
lime, is thrown into endless and most intricate folds, which are laid bare in the 
numerous limestone quarries which are sprinkled over the hill-face ; several of 
these, and markedly the most, northerly, show a peculiar granite vein or belt, 
which generally cuts but occasionally follows the bedding of the lime. This 
vein consists of little quartz, and much of a bluish white, opaque, fatty-lustered 
andesine, carrying imbedded crystalline plates of Biotite. 
Any associated minerals belong to the lime. 
The Biotite is in plates of an inch or more in size, of a dark pinchbeck brown 
colour, a shining lustre, sometimes somewhat greasy. 
Its specific gravity is 2 ° 867. 
1-3 grammes yielded— 
Silica, . : ‘ ; ‘476 
From Alumina, . ; °037 
‘513 .= 38<692 
Alumina, . ; 4 “17661 
Ferric Oxide, . ’ F “255 
Ferrous Oxide, . E » 127952 
Lime, ‘ ‘ 3 al bros 
Magnesia, . ‘ : . Lv ‘d88 
Potash, . ; ; 5 te) OR AL7/ 
Soda, : : ; : *126 
Fluorine, . ’ : , °522 
Water, . : . at 2° 137 
99-963 
Insoluble silica, 1: 391 per cent. Possible impurity unknown. 
A similar vein in the large quarry carries, in addition to the above minerals, 
crystals of delicate green apatite, crystals of brown sphene, of grammatite, and 
of dark-green Allanite. 
2. Found in a quarry on the north side of the road about a mile east of 
Laggan Inn, Inverness-shire. 
The lime, which has a north-north-east and south-south-west trend, contains 
little else than a fine-grained chlorite, and this is immediately associated with 
the Biotite, which is usually imbedded in the former in thin plates of an inch or 
two in size. Its colour is bronzy. 
