Basic Iron Silicate is Fe7SiO10, but this is solidified molten copper slag; set from its first molten state; perhaps bubbled from the process of forming scoria blocks. These are very heavy and smooth, with very fine surface folds. Probably 22% iron, 60% silicon, 7% Aluminium, 7% Calcium and 1% Magnesium, together with other attendant elements. 50mm across and 200 grams. These two pieces were from the Carnsew Pool edge.
