What aspect of a flake ensures it can be effectively used?

The sharpness of a flake's edges is crucial for its effectiveness in various practical applications, such as cutting or scraping. When creating tools from stone, the objective is often to produce a sharp edge that can efficiently perform tasks like hunting, butchering, or crafting. A razor-sharp edge enhances the tool's ability to penetrate materials or perform precise actions, making it more functional for the user.

The thickness of the flake can influence its durability and weight but is not the primary factor determining its effectiveness. The type of stone used does play a role in the flake's overall utility because different stones have varying levels of hardness and fracture patterns, but without sharp, finely honed edges, even the best stone cannot be utilized effectively. Finally, while the pattern of markings might tell us about the flake's origins or methods of production, it does not directly contribute to the tool's ability to perform its intended function effectively. Thus, sharp edges are the key characteristic that ensures that a flake can be used effectively.