Not familiar with those. They are equally as hard to see knapping evidence as quartz evidently. We see quartz in diagonal veins many times here as well as quartzite. It can naturally shear off and leave fragments much like what you have pictured. That is not an artifact IMO (In My Opinion).
I can at least confirm that it is quartz. It's possibly a beat up small stem. And it's really the last two photos that make me think possibly. I might think different in hand, but I've seen my share of beat up/crude in quartz, since in dominates where I hunt. Inconclusive, I guess, based on the photos....