What a collection and a nice refreshing take on the challenge. I find the black material's texture a bit distracting, it seems to make it hard to see the shape and texture of the artifacts.
This is an excellent idea, however, it could have been set-up much better IMO. Here goes ... the backround material is distracting, sand or a plain earthy color might show off the arrowheads more. The pieces should have been placed closer to the center, I like the circle composition, and the top one shouldn't have been cropped out. Lastly more color !! I'd like to see your "unbroken" artifacts someday. My husband and I have walked many miles and seen a lot of country in search of these little treasures.