Banded Chert

Tumbled, as seen in this video: https://youtu.be/yJVM0ldAdxw

Chert is a hard, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture.

Chert is very hard (H = 7) and varies in color. Some types of Chert are Flint, Jasper, Common Chert, Chalcedony, Agate, Onyx and Opal.

Chert has been used to produce weapons such as knives and spears but also to make fire since it produces a spark that can ignite a flame.