PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 45 
cient to have effected any marked change. If it be a hydrated mica the amount 
of change is much greater than mere appearance would indicate, and care was 
taken to exclude, as far as possible, the altered portions. It may be an 
altogether different substance, intermediate between Voightite and Jollyite. 
PIHLITE. 
This species, hitherto unrecognised as British, is possibly not uncommon. 
Probably it is the chief material of the very peculiar schistose rock, which, 
plentifully studded with imbedded crystals of andalusite, forms the trough of 
the small sandstone basin of Lumsden and Kildrummy. 
A very similar rock, only carrying crystals of actynolite instead of andalusite, 
occurs stretching from north of Mulben up the valley of the Burn of Achanachy. 
The rock of the first of these localities is largely quarried in the Coreen hills 
and in Glen Mid Clova, being used in the district as a paving, and also to a 
smaller extent as a building stone. 
It is, doubtless, due only to the perfect seclusion of the district that the 
peculiar excellences of this rock are elsewhere unknown, seeing that it 
possesses qualities which fit it for its use as a paving stone, which are superior 
to those of both Caithness and Forfarshire. 
Splendidly bedded, and with a most convenient dip, it can with the greatest 
possible facility be raised in slabs of large dimensions, of any required thick- 
ness, from an inch to a foot or more. 
Quarried on the very summit of a hill, the trouble from water is so small 
that the little that occurs is actually stored for drinking purposes, and the car- 
riage is aided by gravitation through a descent of some 900 feet. 
The stone itself, being in its general mass formed of a material which yields 
to blows, is readily cut and fashioned ; but this material, being acted upon by 
atmospheric agencies with extreme tardiness, “resists exposure ;” while, inas- 
much as its softer mass is everywhere studded with closely-packed crystals of 
one of the hardest mineral bodies known, it long resists the wear and tear of 
friction ; and, as these enduring crystals project above the softer portions of the 
stone, slipping on its surface is noways to be feared. 
The flags are, moreover, full of beauty. The micaceous particles which form 
the layers are arranged not in flat, but in minutely undulating disposition ; 
they reflect a tremulous lustre, something between a nacreous glimmer and a 
silver sheen, while the dark brown of the andalusite crystals stipples this with 
a peculiarity which is quite unique. 
The writer was formerly acquainted with a gentleman whose most suc- 
VOL. XXIX. PART I, M 
