Not trying to be funny but, it still looks like a natural rock to me. Good luck and keep hunting because there's plenty more artifacts waiting to be found out there.
I see no evidence of that stone ever being altered or utilized by man.
Saying that, and before you argue with us, I give you this assessment with 53 years of collecting experience which is practically my entire life. Others that responded in kind have as much or more than I so we are not trying to mess with you. We are trying to help. I hope you choose to listen to us. Thank you.
Tell us this, what would its possible use be? It is not chert either as the flake off the edge proves. It is softer and has cracked by natural forces or machinery. Tools were made for a reason hence the same similar shapes are found far and wide. That is just a rock. Keep looking and you will find a real artifact.
If you were to hold this and see the flaked edge of the blade side. . . and recognize that the hand side is carefully cut out. . . and see the rubbing of the ellipse on the hand side and the groove made on the side, you'd recognize the artifact here. Photos don't really help much, unfortunately. This, in my estimation, was a paleo or archaic hand axe or chopper, which was used---and the large chip came out during use, rendering it useless as a tool, thus the owner considered using the rock for smaller tools.
There are man made stone artifacts that fall under the heading "problamaticals", meaning they are either clearly man made or they show utilization by humans, but their purpose or function is unknown. Sometimes they are one-offs, so they won't likely appear in artifact guides. Sometimes they are well known classes of artifacts. Plummets would be one such example of such a class, several theories having been offered to explain the function of plummets.
Nobody has ever said one cannot find a one-off artifact that falls into the heading "problematical".
However, what does not prove questionable, what is not subject to debate, is that experience studying both rocks and artifacts brings individuals to the point where recognition does become second nature, and it becomes extremely easy to recognize when a rock is a rock, and an artifact is an artifact. This is a skill set in essence, and it takes time to bring one's skill in distinguishing rock from artifact to that second nature level.
Usually, but not always, people who insist that a rock is an artifact lack the needed experience to have that skill set. As well, they usually don't understand that distinguishing rock from artifact requires time and experience. In a virtual format such as an online artifact forum, the needed experience cannot be transferred to the uneducated beginner. It takes time, and as we see so often here, some people refuse to learn. They refuse to understand these things take time. It's a skill set and it's a learning curve. Simple as that. Folks who have that skill set, born of experience, can render accurate opinions very easily and quickly. Sadly, sometimes you can bring a horse to water, but you just can't force him to drink it.