If it is the iron stone type material I am familiar with, I am sure you could cut a flint out of it, but I doubt it would last for more than a few strikes since the edge would powder most likely. Since I don't know for sure what you are calling ironstone, I don't know. The pertrified I am using is very hard, but it is also tuff. It works very well until the stone starts to go, and then it comes apart in chunks, not chips. By far the best sparking stone I have is black flint. It is soft, but it breaks to a very sharp edge. Since I have been playing at learning to knap, I have a piece of a gritty textured agate/jasper material I have knapped an edge on. I tend to grab it to open boxes or to cut small stuff here at the computer. It works pretty well and is pretty nice for that or arrowhead use. I am not sure how the material would hold up to the impact on the frizzen because it has that gritty texture to it. Now, a piece of good bloodstone is the best I have used so far. It isn't as sharp as some, but the edge lasts forever. Not gonna make a lot of flints out of gem grade bloodstone tho! Sorry I could not really help.