@SteveE beat me to it but here is some of my thoughts.
Here is the WIKI for Metal clayhttps://en.wikipedia.org/wiki/Metal_clay
The binder burns away, leaving the pure sintered metal.
I do mostly ceramics but have taken a few classes using the silver version of the Metal clay.
In any case, the stuff handles much like clay.
At one time I looked up one of the patents and it went into extensive explanation of the stuff.
I do not remember if the patent information discussed what or how the metal part was made into the fine particles. That is why I suggested that @SteveE look up the patents and report back.
@SteveE might even post some links to some of the patents.
(This would keep us within the spirit of our forum rules.)
As an aside
It appears to me that the Base version of Metal clay could be used for many citizen science projects.
Even the PMC version could be used as well, if you can stand the cost.
A reminder that the metal is sintered and not as strong as regular cast metal.