This is an unusually important question. Could one determine the approximate age of a manufactured bismuth/magnesium/zinc composite somehow by the effects of UV, cosmic rays, or some other type of energetic particle acting on the material? For example, by microscopic examination or by some other means, could one estimate the number of cosmic ray impacts on the material and from this estimate the approximate amount of time since the material was manufactured. Also, does any kind of isotopic change happen over time; perhaps again due to cosmic rays or the like? If we could determine the age of this composite to within 10 years or so we could probably proceed. We are assuming that this was made in the 1970s. We have the material but we cannot identify the manufacturer. It is imperative that we can estimate the age of this stuff. Any suggestion? The potential cost of testing is not a concern.