I thought we hashed this out--it's bismuth. All bismuth does is offer a similar PM capacity without the annoyance of lead vapor, at several price multiples with respect to assay lead.
Bismuth can be dissolved in dilute nitric acid, FYI. Personally, I wouldn't do that. I wouldn't even use it for capturing PMs. Lead is much easier to separate and costs much less. Even better is silver!
Lou