True tinder fungus, Chaga, takes a spark almost as good as charcloth, but not quite. I have been collecting interesting looking rocks as I'm out and about and found one which I believe is chert, and another which is unknown, but appears rusty in spots. They will throw a spark, but it is usually just a single and it takes hitting them just right to get the spark. I've tried both chaga and charcloth, but have yet to get an ember.
