Judd - while I applaud your efforts and "outside the box" thinking when looking at rocks to determine if they are artifacts or not, you're missing the main ingredient. None (or at least none of the ones I've seen you post yet) have ANY indications that they've been worked by any human hand.
The texture of the top(white) is Very much different than the bottom. The back texture (reverse side) is completely different from the front , top or bottom. The Perfect placement of the groove separating top from bottom,black from white doesn't appear to be natural either. It stands on its own very well too. And if you noticed I haven't (in this reply nor the post) used the term "Artifact", "Effigy" or relic. I wanted to see what kind of responses I would receive.