Chert / flint & how I find it. "Flint" in geological terms only refers to chert formed in chalk or marl (like in the Dover Cliffs, England). "Flint" in archaeological terms refers to chert that is usable for flintknapping, and most people are familiar with this meaning. Chert can be a wide variety of grades, some of which can be knapped, others that are too chalky, tough, or large-grained. The amount of organic material in the original deposit determines the quality, and often the color as well.