256 PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 













dorite is distegrated and dissolved at a faster rate than the augite, so that the 
latter is left protruding from the surface of the surf-beat. chity with a false 
appearance of being the better crystallised mineral. 
The labradorite here occurs in grey crystals, which are minutely striated ; 
they are possessed of little lustre. Its specific gravity is 2° 831. 
1:°567 grammes yielded— 
_ Silica, 3 804 
From Alumina, 022 
* 826 = 52°411 
Alumina, : ; .  28:959 
Ferric Oxide, . . F -149 
Protoxide of Manganese, . °913 
Magnesia, : : : * 54 
Lime, ; , ‘ + LORS 
Potash, .. : ‘ : 1°61 
Soda,./ . : : "485 
Water, . ‘ ; ; 927 

ae 99-844 
7°73 per cent. of the silica were insoluble ; possible impurity, augite. 
Immediately to the back of a store, south of the battery, there is a thin vein 
of granular grey labradorite, with imbedded lustrous white crystals; this 
is here the matrix of splendent crystals, either of the pseudo-hypersthene variety 
of augite, or more probably of diaclasite: the habit of the labradorite has, there- 
fore, within a distance of about fifty yards, in every way altered. A fine polished 
slice wer this vein is in n the Industrial Museum of Edinbugh. 
From Micaceous Geiss 
Scattered sparsely over the hill slopes, built into the dykes, or gathered 
into the road-metal heaps, there were at one time found, in the parish of Kil 
drummy, in Aberdeenshire, masses of a seam stone, consisting of an extra- 
ordinary tough matted mixture of crystals of red andalusite, white fibrolite, 
lepidomelane or Biotite, margarodite, and cream-coloured labradorite.* 
A plicated double skin of mica on all the specimens showed that the gneiss 
had been the matrix, and that they had not been borne far from their original 
site. 
ey 
Edi 
| 
* The late Rev. Mr Morean of Stonehaven had so great an admiration for these specimens, that h 
was wont to spend months in wandering over the Kildrummy and Clova Hills in search of them ; 
so thoroughly had he scoured the district, that. the present writer, who has made repeated journe 
with the same object, was never successful in finding either the original locality, or a single specimen. 
