Lewis gneiss

I don't know huge amounts about geology but I do know a nice rock when I see one. 
Scotland is one of the best geology places in the world as we have some of the oldest rock formations here on the planet. Assynt and Lochinver area is now a designated geology park. The landscape there is incredible. This however, is Lewisian gneiss from the Isle of Lewis 20 miles across the water from there.