Long before matches were available, flint and steel were used for firemaking. A spark is created by striking the steel across the edge of the flint or some other type of quartz rock. Tiny flakes of metal are chipped off. The action heats the flakes to the point they catch fire. The burning metal flakes or sparks are directed to material which burns easily. This may be dry plant or wood material. Most people carried a much more reliable material called char cloth. The usually cotton cloth was prepared by first charring in a fire then smothering. Once the cloth is ignited by the sparks, it is then transfered to a bundle of tinder and blown into flame. The ranger in the picture is demonstrating fire making.
Both the pioneers and American Indians used flint and steel. The steel was a popular trade item for trappers and explorers trading to tribes in exchange for other items.