Striped Flint Slab - Poland  cca 1944 g - 23x12x4 cm

This is an  slab of striped flint, collected from the Swietokrzyskie Mountains of Poland. This form of flint is considered rare and typically displays a beautiful banded and striped pattern, hence its use today in jewelry. It is Upper Jurassic in age, meaning it was deposited roughly 160 million years ago.

 Striped flint, also known as "banded flint" is a type of flint exhibiting concentric banding alternating between light and dark bands. This banding can vary in color, however the colors are most often hues of brown. It is believed to have formed by precipitation of silica directly from seawater and is found as concretions within limestone deposits. The crystallinity is typically higher in the centre of a concretion.

 Most striped flint is mined from a deposit in Poland, near the cities of Sandomierz, Ostrowiec Świętokrzyski and Iłża. It is found in deposits that are Upper Jurassic (Oxfordian) stage in age, or approximately 160 million years old.

 Because of its rarity and distinctive look, striped flint from Poland is often used in jewelry. It's use goes back thousands of years. It was mined in the area by Neolithic people around 4,000 BC, and used in the manufacturing of stone tools.