Copper Sulfate I think
I mixed an old partial bottle of this on Monday - the bleach still is active, but the dried out then re-dissolved sepia toner was kaput.
The bleach is blue, which to me is copper. I have a formula for an alternative c41/e6 bleach based around copper sulfate, which is also found in nurseries as a growth erradicant for around patios, as I recall.
I have not tried to mix my own copper bleach, untill my ferricyanide supply runs out; it works fine for me. I just turn it in at the HHW depot when I go there to hand over spent fixers. I do have copper, but just to do copper toning.