PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 61 
the gneiss, which dips to the south-east. The serpentine along the coast is very 
inaccessible, on account of its extending but little inland from a line of precipi- 
tous cliffs. The small protruding point was many years ago chosen as the site 
of a lighthouse. The works connected with the cutting a foundation platform, 
and the building of a pier exposed the stratum, and showed its relations to 
the gneiss. This spot acquired some interest shortly after the building of the 
lighthouse, on account of the mineral zircon having been first here found in the 
British Islands by Parrick NEILL in 1811. The crystals of zircon, which are 
very minute, lie imbedded in the mineral analysed. This constitutes a bed of 
about a couple of feet in thickness; its colour is a very dark green; the larger 
bed is divided into smaller, differing somewhat in structure. The general mass 
which contains the zircon crystals is hard, somewhat coarse and slaty; it carries 
veins of steatite, Dolomite, and thinner portions of chlorite itself, of a structure 
which is softer, minute-granular, or even scaly. The scales, however, are so 
minute that they are hardly recognisable, and this closeness of structure has led 
to its having been called potstone; at least potstone has been said here to 
occur, and this is the only substance which I found at the locality likely to 
have been mistaken for it. 
The specific gravity of this finer-grained and purer variety is 3° 099. 
1-628 grammes yielded— 
Silica, : . °465 
From Alumina, . *036 
* 501 = 30° 405 
Alumina, . : : a E256 
Ferric Oxide, . ; eer ono 
Ferrous Oxide, . . LO Ee 
Manganous Oxide, . ~ grag 
Lime, : : ; . trace 
Magnesia, . . 30° 634 
Potash, =: ; : : Saal 
Soda, 5 F : » 306 
Water, : jcmict a AS 
99° 921 
1:3 per cent. of the silica were insoluble. It possibly contained a very 
minute quantity of magnetite, as crystals of this were seen in other specimens. 
2. From half a mile south of the farm of Corrycharmaig in Glen Lochy, 
Perthshire. 
The rock of the district is a mica-schist, with veins of a peculiar claret- 
coloured hyaline quartz carrying chlorite and rutile. 
At the locality whence the mineral was taken, chromite had been wrought. 
