Why have no alleged pieces of exotic crafts ever been subjected to rigorous, secure, transparent, instrument-based analysis?

People like Art Bell and Linda Howe and others claimed to have owned pieces of the Roswell craft, some of them larger than just microscopic flakes. They're far from the only people who claim to have had artifacts of NHI tech (e.g. alien implants). It would be so simple to develop highly convincing evidence of NHI tech if you already had one of these fragments. Using a technique called atom prob e tomography (machines sold by a company called CAMECA), a technician can whittle a tiny piece of m...