The recipe for black holes is literally the simplest recipe possible; it’s “get a bunch of stuff and put it somewhere”. Everest into a black hole it would be no more than a few atoms across. 4 micrograms doesn’t have a scary amount of gravity, and if you turn that into a black hole, it still doesn’t. “Natural” black holes in space (that are as massive as stars) radiate so little that they’re completely undetectable (hence the name: black hole). The real danger of a black hole of this size isn’t the black hole itself, so much as the process of creating them (listen, I’m making a black hole, so I need to crush all of Australia into a singularity real quick).