First, if you don’t watch the YouTube Channel Applied Science you are missing something very interesting. He makes (in his garage) things like Electron Microscopes, X-ray machines, even a CT Scanner. Once you watch him make these incredibly complex devices, it’s easier to understand all of the general concepts behind them. I’m not affiliated, just a fan.
Second, in this video he covers those handheld X-ray element analyzers. Complete with demo, explanation and a teardown. The device will show you what’s in (nearly) any element or compound with accuracy down to 2 decimal points. You just put it in contact with the material and pull the trigger.
One crucial aspect that I didn’t realize until watching this video is the the devices don’t detect Oxygen. But that isn’t a deal-breaker, this would still be a powerful addition to our tool-chest.