Yes, beryllium is very nasty. You don't ever want to breathe its dust, so don't machine/cut/grind it ever. There are usually warning symbols on things containin

Yes, beryllium is very nasty. You don't ever want to breathe its dust, so don't machine/cut/grind it ever. There are usually warning symbols on things containing it. But it has applications so it gets used. For example, it is used in spacecraft to save weight over aluminum. When I worked with MRI machines, we used FETs with beryllium oxide ceramic (BeO) backing. BeO is an amazing thermal conductor, electrical insulator (only diamond is better).