TRANSACTIONS. 
I.—Chapters on the Mineralogy of Scotland. Chapter Fifth—The Micas ; 
with description of Haughtonite, a new Mineral Species. By Professor 
HEDDLE. 
(Read 3d February 1879.) 
MUSCOV ITE. 
Muscovite is so easily recognised by its optical properties that the only 
cases which seemed to me to call for analysis were those which, from being 
possessed of characteristic colour, were of special interest. 
Of these the most singular is a variety found rarely in the great vein of Ben 
Capval, Harris ; it occurs in crystals of a peculiar green tint, the crystals are 
small and have somewhat of a pearly lustre. 
On 1-2 grammes— 
Silica, : : ool 
From Alumina, . “a6 
aye = 43 +083 
Alumina, . , ‘ iy a2" 858 
Ferric Oxide, . } ; Wao 
Ferrous Oxide, . b ~ | 2764. 
Manganous Oxide, . 2 083 
Lime, ; : : 2 LOK 
Magnesia, . : , ; 333 
Potash, . ; : ~. 9084: 
Soda, : f : : 847 
Water, . 3 : nee) 22 
dor 983 
Loses in bath 2° 793 of the above water. 
It would thus appear that the ferrous oxide is the source of the colour. 
VOL. XXIX. PART I. A 
