Krzemionki, Opatowskie, PolandPolish Flint occurs as nodules in sedimentary rocks, such as chalks and limestone. It is a member of the chalcedony family. The polished faces of these three fine examples reveals the internal layering for which this mineral is known. Banded flint, only occurred in the Jurassic limestone in Poland (160 million years ago). During the Neolith Period (5000-3500 years ago) flint was mined for the production of tools (axes, arrowheads, knives, etc). These tools were exported as far as the Netherlands and the Black Sea. The ancient Polish Flint mines were only recently rediscovered in the twenty century. Measuring 7 3/4 x 4 1/4 x 1/2 in; 7 1/4 x 4 x 1/2 in; 7 x 4 x 1/2 in (19.5 x 11 x 1 cm; 18.3 x 10 x 1 cm; 18 x 10 x 1 cm), respectively. (3)