




220 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 
12. From large masses,—probably from Brathans,—which were found loose in 
a mole which crosses the Loch of Leys, near Banchory. In large crystals of a 
white colour, quite fresh, but very opaque and lustreless, associated with Haugh- 
tonite; specific gravity, 2°542. 
On 25 grains— 
Silica, B ; 2 15° 245 
From Alumina, . j * 9325 
TSR = oo 
Alumina, . : ; ; . 18-98 
Ferric Oxide, Z - ’ , * 982 
Time}: . . : : , : ‘88 
Magnesia, . 5 : ; 569 
Potash, : : : : » La '706 
Soda, . : : : : Be Po OS 
Water, 5 : ‘ : d * 34 

100° 261 
Insoluble silica, 1°82 per cent. Possible impurity, quartz. 
13 and 14. From a tilted granitic band in gneiss, exposed in a quarry about 
half a mile south of Struay Bridge Inn, Ross-shire. This band much simulates 
a dyke, but it follows obediently the contortions of the gneissose layers. The 
associated minerals are a brilliant pale olive-green muscovite, tourmaline, and 
garnet of a lively red tint, in a paste of hyaline quartz. 
The orthoclase occurs of two very different appearances. 
That which arrested attention, and led to the analysis of both, is of a 
saccharoid or large granular structure. The crystalline facetts, lying in every — 
direction, with a high lustre, give it a spangling appearance, like statuary 
marble ; and the colour being precisely that of the pink variety of petalite, 
it was taken for that mineral. It was associated with, sometimes imbedded 
in, a lavender-blue, cleavable, somewhat dull variety, which occurred in masses 
of considerable size. 
As the analysis of the pink variety showed it to be orthoclase, the blue was 
likewise examined,—it being hardly conceivable that one and the same sub- 
stance could assume, in. juxtaposition, two such diverse structures and colours. 
