Polished North Sea flints - bag

Bag of polished flints from the North Sea.

flint
Flint is a variation of fine-grained quartz (chalcedony) that is found in many places around the world and its name comes from its historical function as an important tool for making fire.
Flints are often black or grey in colour, but can also be yellow, brown or even red, depending on the inclusions they contain, such as hematite (iron).
Due to its beautiful structures and colors, flint is also often used as a gemstone.