You get some real good sparks with that steel. It's a pity quartz chips so easily, but it does give off a decent shower.
I still haven't tried making char cloth, but I saw David West made a video on how to make char cloth easier to spark by protecting it from the hottest part of your tin. You might find it interesting:
I'm not sure what this stuff is but our front garden beds are full of it, sold as "rainbow stone". I assume it's some kind of quartz. Pretty fiddly with it being so small but thought I might as well give it a shot, and can get sparks off a 1084 knife spine but no ember yet. Might make a little striker next time I fire up the 2 brick forge.
It does chip pretty easily but there's plenty more where it came from!