Jerry,
Even though the word has recently been rejected as legitimate, Alcan 6 is 'ungoogleable', something I'm sure you are already aware of.
Your best bet is going to be looking for old Alcan advertisments or better yet, looking more closely into the paperwork that may have been in the estate you acquired the powder from. I cannot imagine that the previous owner didn't keep some sort of record what he was using the powders for & it is quite likely that he had the data you seek from Alcan in his ref library or loading records.
FWIW, I'd think the canister & its contents quite rare. In the same breath, I'm sure it was known in Italy under another name. That too might be a line of inquiry worth pursuit.
