Describe the test and the rationale behind it. I have provided rationale that a functional test is not a valid test in this case. The rock I have chosen as an arrowhead might even be black whereas the known arrowhead is red. Does a color test matter? I have given what I think is valid rationale to exclude a functional test.
Okay, in order to shorten this hypothetical exercise, I will state that I will perform a functional test on the arrowhead, which you say is required but I say is superfluous.
We determine that my potential arrowhead was identical in every aspect to the sample except the material "used" which results in a different weight and color. We attach the potential arrowhead and the sample arrowhead to identical shafts in an identical manner. We use the same bow to shoot the final arrow at bison(we are cruel testers). The sample arrow penetrates the bison and the bison eventually dies. The potential arrowhead shatters on impact with another identical bison. It fails the functional test. Was it an arrowhead fashioned by intelligence. You evidently would deny that it was an arrowhead. I would disagree. Let others decide.
If one shattered and the other one didn't under identical test circumstances, then there's differences in the material they're made of beyond just weight and color. I'd question the intelligence behind soapstone arrowheads.