What is this black rock? I found it beneath the waters of Lake Ontario near the shoreline, it is a dark greyish-black with small flecks of mineral deposits on it that are visible in the light. The acid test resulted in NO fizzing, and it is non-magnetic. Tried chipping it off, wondering if it was painted, and it remained black, there are fine streaks on it as well that you might be able to see on the photo. Tried drilling a hole in it to see for certain if it was black and was BARELY able to make a dent, a hammer only scratched the surface so it is very durable. Hardness level is a 6-7, and it left a grey streak on paper.
Luster is obviously non-metallic, it is very smooth but that might be because from the water hitting it where I found it. It does have some imperfections all around it but you can't feel it, it is also on the heavier side.