I've seen ceramic media advertised, but it's quite expensive. There is also "pin" media, which is made of short steel pins, as if made of chopped up sewing pins.
If it's a question of tarnishing, there are a number of metal de-tarnishing chemicals that work amazingly well. My mother-in-law showed me one she used to on a collection of really old brass and silver buttons. The buttons were black with tarnish. She dipped them in the chemical, and it made them bright instantly. I can't recall the name of the product, but I understand that there are several competing products that work the same. I think it was "mister metal" or something like that. I just looked up one and it's called Tarn-X.
If it's corroded green, I'd throw them away and start with new brass.