Gunflint is a term used for a type of rock that was widely used in the production of flintlock firearms. It is a hard, dark-gray or black-colored stone that is highly flammable, making it perfect for use as a spark-producing element in these weapons. However, if you are looking for synonyms for the word gunflint, some of the most appropriate terms would include flint, chert, agate, jasper, and quartz. All of these materials share many of the same characteristics as gunflint and can be used as substitutes in the production of flint-based weapons or other tools that require flint.