You need the Hamilton Jenkin Truro to the Clay District book. Rather than shelling out the fortune, get it from the library.
According to the 6" maps. Savath Clay Works is just west of Outer Savath and Ham Jenks notes say "Savath or Savath Hills Iron Workings". I assume the whole thing was obliterated by the clay works. Criggan Tin Mine is on the maps with a couple of engine houses, this is between Savath and Criggan clay pits, just NE of the railway cutting (which may also be obliterated by now).
Stu