Appropriate stone was a necessity for tool making for the Native American. Unfortunately, large tracts of central Nebraska had little stone resources. Along the Republican River, and its tributaries, in southern Nebraska was a silcified chalkstone known by several names: Republican River jasper, Niobraraite, and Smoky Hills jasper. This stone was used to for many tool forms - points, scrapers, blades, etc.
Coined as the 'true buffalo skinning knife' was the Harahey knife - named after a native village in Kansas. It was generally a diamond-shaped, double pointed blade, beveled on four edges...often taking on a propeler-like shape after many resharpenings. It was in common use on the plains around 700 - 350 BP. Pictured is an actual artifact of Republican River jasper. It measures almost 6 inches long, by just over 1 1/2 inches wide, and only about 3/32 thick. Boy...if only I could consistantly knap blades that thin...lol.