°To shape a hard, brittle material (such as flint, obsidian, chert etc.) by breaking away sections or flakes, often forming a sharp edge or point. Distinguished from "carve" because each fracture goes across one entire face or facet, and from "cleave" because breaking (knapping) vitreous, brittle homogeneous (i.e., not crystalline) materials inevitably results in curved, conchoidal fractures.