PENMAENMAWR 
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clearest of opaque granular enclosures, due probably to some 
amount of decomposition. I saw no similar specimen cer¬ 
tainly in situ, but one or two in such situations that I have 
no doubt of their being derived from the mountain imme¬ 
diately above them ; and one of them occurred in a part 
which was much more obviously and coarsely crystalline. 
This border portion has occasionally a well-marked conclioidal 
fracture; one specimen shows concentric rings, though unfor¬ 
tunately they are not perfect. 
In one of my specimens from this fine-grained border of 
the mass, a very remarkable felspar crystal occurs. It is one 
of the larger ones—probably of an older generation—which 
imparts a slightly porpliyritic character to this part of the 
rock ; but only one end is visible, and that is of an irregu¬ 
larly oval shape. Over the greater part of the extent of the 
section there is fairly normal twinning, with angle of 48° 
between the extinctions of the two sets of lamellae, which 
suggests labradorite ; but all round the visible edge there is a 
narrow zone, which is apparently of such different compo¬ 
sition that its optical position is quite different from that of 
the kernel so to speak, although it is obviously continuous 
with it as to its crystal shape. It extinguishes so very nearly 
at 45° from the direction of the trace of the twinning plane 
that it is difficult to say whether it is twinned or not, but I 
believe not. Strictly speaking, it appears to be made up of a 
considerable number of very narrow parallel zones, with 
very slightly different extinction angles. 
The ladders already spoken of land us at the level of the 
quarry, or very nearly so ; and from the pathway round the 
corner of rock which we have to pass, the views over the 
country westward and Anglesey are very fine. Possibly as 
we linger here out of sight of the working, we may be sur¬ 
prised to see what seems like a fog drift over us and pass 
away up the valley to the south. It is, however, dry, and 
smells dusty, and is the dust arising from the throwing down 
the seaward face of the mountain the waste stone of the 
quarry. The quantity so disposed of is enormous, amounting 
sometimes I was told to 1,800 truck loads per week, and has 
resulted in the disfiguring fans of bare stones which are so 
unfortunately conspicuous from Llanfairfeclian. 
In the quarry we find that we are on the highest of three 
floors, each of which is being extended further and further 
into the hill, while the edge of each of the two upper ones 
is being invaded by the one immediately below it. The stone 
is worked in the usual manner, the jointing of the rock being 
taken advantage of to reduce the labour of getting it down. 
