I'm gonna vary from most of the responses.
It's a shame to waste powder.
I'd see if I could find some "known" 700X, and visually compare a handful of both.
If it looks like 700X, I'd try a load, at the VERY low end of the load data for 700X to see what happens.
Since 700X is at the "fast" end of powder burn rates, it's unlikely that you will load anything dangerous, if you stay at the low end to start out. Once you establish that it does respond like 700X, you can start load work-up.
This is similar to what the folks do that shoot the pulled down "surplus" powders. It's not like you will be using an unknown really fast burning powder in a rifle load that needs a slow burning powder. Keep it to light pistol load data for fast burning powders, and see what happens.
Or, box it all up, send it to me, and I'll "dispose" of it...