Can you use another type of rock instead of flint?

Yes, you can substitute other minerals for flint, but in terms of its ease of use you really can't compare any of these with flint. It gives you flat and sharp edges that possess a strength comparable to that of diamonds (it is thanks to this property that it was used by ancient peoples to make stone arrowheads, knives, axes and other such tools). It is very easy to place a piece of tinder on such a flat share at the moment when you strike a spark. If you have the knack for it, it is possible to swap flint for quartz, for example. We've often done this for demonstration purposes while taking part in tourist exhibitions and festivals.