Another erratic which has dropped out of the Irish Sea till at Abermawr. It's obviously very ancient and has a heavily weathered surface, but the striking thing about it is the presence of these large pinkish crystal agglomerations which are slightly reminiscent of the spotted dolerotes at Carn Meini and Carn Goedog. The surface of the stone is pinkish brown, but when it is broken open the interior is seen to be very hard crystalline blue-grey.
Anybody prepared to hazard a guess as to where it might have come from?
Looking through some old photos, I also found this -- an erratic found on Newport beach, in an exposure beneath the sand dunes. Could it be from the same place?
Now we have another suggestion from one of our blogging community that maybe this is a porphyry. Here is the idiot's guide to volcanic / igneous rocks:
and this is what porphyry looks like.
Well, not identical, but maybe in the right general area. And there happens to be a source of porphyry on Lambay Island off the Irish coast near Dublin. I haven't been able to find a good photo of what this particular porphyry looks like, but it would of course make perfect sense for erratics from Lambay to be incorporated into the Irish Sea Glacier, transported southwards, and then dumped in glacial deposits on the North Pembrokeshire coast.