Many years ago (1967) I found a broken piece of marble which had been smoothed and polished at what seems to be the site in your first link. It was about the right thickness for a kitchen worktop, but sadly only about a 6 inch rough triangle.
I have been too busy to get back to Skye since then, but I do get to Oban and Fort William every few years. Sadly I was disappointed last time, McTavish's Kitchen in both towns had gone.