Core

A black or gray zone in the interior cross-section of a vessel wall, usually associated with incomplete removal of carbonaceous matter from the clay during relatively low-temperature firing; not to be confused with black coring at high temperatures, which results from trapped gases and may lead to bloating

Any lump or nodule of stone from which flakes have been intentionally removed. Frequently, cores are of special types, shaped to facilitate the removal of particular blanks like blades or bladelets, or large oval flakes with a sharp edge all round.The most distinctive cores of the last-mentioned kind are called tortoise cores, from their resemblance to that animal, and are associated with Leval-Coisian technology.