Flaked obsidian biface

This replica measures 7.5 x 5 centimeters.

A 'biface' is a tool with 2 surfaces and, usually, a more-or-less continuously worked edge around the perimeter. A biface itself may have been used as a tool, or as a source of useable flakes (a core), or it may simply have been lost or disgarded unfinished, at some stage in the process of tool manufacture.

Sometimes, when archaeologists cannot be sure if a stone tool was a projectile point, a knife, or other tool, it is simply called a 'biface'. The final interpretation is left up to the beholder.