Mike
As far as I know green chrome is chromium oxide. Most of your knife maker supplies carry it" Sheffileds, K & G, Texas Knife Makers supply, Kovals ETC.
I imagine you can find it at most of the wood working places like Woodcraft, Wood Workers Stroe, & Rockler.
I have never used a cork belt, I do use green chrome on a sewn cotton buff, for blades and nicklesilver fittings.
Jim A.