Most people think that the ubiquitous flint and steel is only possible with steel, which it is, and only possible with flint, which it isn't. Contrary to popular belief, quartz also works because it is the same list of ingredients as flint, which is silicon dioxide, but crystalized in a different manner. Churt and steel is actually more common due to the abundantly of churt, another mineral made from the same ingredients crystalized in a way between flint and quartz. The reason that flint and steel is so ubiquitous is that quartz doesn't work as well as churt, which doesn't work as well as flint for sparkmaking, and the ubiquitous flint and steel is the highest success rate-type pyroplasmic instrument in a range of 3 others. Nothing else to say.