only real way you can get an AVERAGE (because not all will yield the same and not all methods get the same amount returned) is to do assays of a large mount of material. As you do more and more, your average will get more accurate. I would say that the only way you can get a reasonably accurate method is to send the material to a ewaste recovery specialist. There are some out there and they will happily give you assay results (for a fee). This is about the only way you will get a close approximation of how much material is in X item on average. And do not forget, gold is just ONE of the materials that can be recovered....people forget that many times there is a silver or copper mask for the circuitry before it is gold plated....those materials are well worth the recovery too (only in LARGE batches from what I have read).



Not the best answer, but again...most of what you are asking is info that we ALL in the ewaste industry would LOVE to have (keeps us from getting ripped off). The main issues as miked said is that those companies tend to keep that info very secret.