What does the cortex refer to on a stone tool?

The cortex of a stone tool refers to the exterior surface of a nodule of stone before it is flaked. This outer layer often has a rough texture and is characteristic of the unaltered stone material. It's important in lithic analysis because it helps in understanding the raw material source and the initial stages of tool-making. Identifying the cortex allows archaeologists to assess how a tool was manufactured and how much of the original stone was removed during the flaking process. In contrast to the cortex, elements like the sharp edge created during flaking or the smooth area resulting from consistent use relate to the tool's functionality rather than its initial material preparation.