George C. Frison describes a knife similar to the one above  in his book "Prehistoric Hunters of the High Plains", pages 80-81.  This knife, thought to be diagnostic of  late Shoshonean usage from the Late Prehistoric Period, is approximately 500-1,500 years old. 
As one becomes an accomplished lapidary, you quickly realize that the quality of rock or gemstone you choose determines your success.  Likewise, for our stone age ancestors, selecting the right stone or rock was equally important to their success in making stone tools.  The difference being, survival was directly proportional to their ability to collect and tool the proper stone.  Lithic technology is the modern day term used to describe the study of stone tool development.  The partial arrowheads below are a good examples of points made from maybe the best lithic material in the world, the Phosphoria Formation red chert found near Shell, Wyoming in the Bighorn Mountains.  Some believe certain Clovis cultures would travel hundreds or miles on foot to acquire this prized lithic material.  The workmanship on all these archeological pieces is outstanding.   
Also called flint knapping, the process describes physical flaking and chipping of stone to produce usable tools.  Flint is the general used to describe stone which is capable of being knapped.  It is a usually a homogeneous type of material high in silica content.   The supply of good knappable flint  and other lithic materials has always been  limited with studies showing certain Native Americans traveling hundreds of miles on foot to obtain certain types of preferred knappable materials.  
Archaeologists use the general term 'projectile point' or just 'points' to refer to objects affixed to a pole or stick and used as a weapon.   Commonly made out of stone, the point tipped poles or sticks became weapons of choice for killing animals and for personal aggression and protection. The earliest know inhabitants of the North American Continent, referred to as Clovis, approximately 11,000 years before present (BP), are solely responsible for developing  the famed Clovis point.  With this highly successful spear point, some believe the Clovis culture might have killed off most of the mammoths in North America.  True arrowheads are a subset of projectile points and as the name implies, were attached to arrows and used with a bow.  Bow and arrow technology on this continent is recent and dates to about 1,500 years ago.
left click for larger view
left click for larger view
left click for larger view
Most of the above points are from the Ruby Archeological Site, Wyoming Powder River country near Pumpkin Buttes.  The Late Plains Archaic Period cultural group that made these points were bison hunters.
Lithic agate debitage in situ near the top of the Bighorn Mountains, Wyoming at Spanish Point.
Clovis replica of native stone.  Knapped by one of the best, Gary Merlie.
Knapped by Gary Merlie from Native Stone found near the Colby Clovis Site in Northwestern Wyoming.
The controlled heating of some stone materials can alter the physically properties of the stone allowing a before unknappable stone to become knappable.  Tools can then be produced.   But nothing is free, and while a certain type of stone may become knappable, it may also become brittle and subject to easy breakage.  Heat treating times and  temperatures are critical with varying formulas for different materials.  If heated too much,  some stone can actually disintegrate and turn to powder.   Heat treating of stone lithic material is thought to have been first used around the middle of the Archaic time period. 
First generation oven controller for use with the small home made oven below.  Timing control is internal.
Second generation prototype oven controller for use with commercial kiln.  Temps and times are computer controlled with QBASIC programming.
PC board layout for computer operated kiln.  Device uses the parallel output for control functions  with QBASIC programming
Small home made fire brick oven.  Wall-Mart heating element is bent to fit oven cavity.  Temps up to 750 degrees F are obtained.
Looking down the brick oven.  Visible is the feedback thermocouple and oven rack.  A small tray filled with sand holds the lithics.
Second generation kiln/computer setup.  To keep from burning down the house or garage, this setup is wheeled outside during operation.
Copyright 2006 Veta Sciences
Points knapped by me mostly from tri-color obsidian collected at Glass Butte in central Oregon.  The small red points were knapped from Wyoming Phosphoria Formation red chert.