The Cliffs of Moher

[Koen G]

Ah ok, so in addition to the copper nib of the quill contributing additional copper and cuprite,  the  distinct hematite and palmierite components of the red ochre could be directly linked to Ireland.

Do you mean "they had this stuff in Ireland too" or "this points to Ireland specifically over other places"?

The first one would not be surprising, since substances like ochre are abundant worldwide. The second case would actually add weight to your theory, but requires some more argumentation than a link to a commercial website.