Thank you very much Alan. Can you tell me which of the pieces is ore vs. slag? I understand the firebrick one. Also, is the green glass considered slag? The objects came from a 5ft deep trench on top of hill. These pieces are all I have found. The context is prehistoric (Paleolithic) stone tools so I was trying to determine if these can be accounted for historically. The slag was probably buried historically into this context. There is a smithery location 250 yards and 55 feet elevation below the slag find site. It was in operation during the time frame you describe.
An archaeologist friend of mine also found slag in a Paleolithic context and isolated some organic-bearing material in it which was carbon dated to Paleolithic times by the world's top lab for this. I took a sample from the item in the 1st photo which I thought might be charcoal and might also be radio carbon dated. It was not organic and maybe because what I thought was charcoal was actually coal. My friend is trying to get additional dates to see if his slag could be that old.
I think what I have is historical but I'll let you know if he gets any more very old dates. Appreciate your help, thanks for sharing your knowledge.