I think that you are talking about a stellite
material called Tantung G. This material is
indeed very hard to grind. I have made a few small knives from this material which I obtained in the form of lathe tool bits. This
material is much harder & more brittle than
the stellite products normally used by knife
makers. Besides being prone to chipping, it
is hard to find in larger pieces and is quite
expensive. On the positive side, it finishes
beautifully and holds an edge nearly forever.
Let me know if you have any other questions.