Mystery Rock

Recently, I was helping my uncle and aunt with a computer problem at their house. As I was leaving I noticed a rock on the counter that was kind of odd. It seemed heavy like metal but my uncle ran a metal detector over it and it did not trigger it.

It looked like it had pyrite in it but some of it was reddish-orange as if it was oxidizing. The pyrite is at the top of the rock and seems to be about 0.25 inch wide with some showing through at the top surface in a ring shape.

My uncle let me have it and told me it had come from a relative's pond in southern Indiana. Some oil had leaked into the pond from an accident and they had to drain the pond. At the bottom they found some rocks like this one.

It is kind of in the shape of a nut going to a bolt but I put a rare earth magnet to it and nothing happened. I took an ohm meter and it showed about a megaohm of resistantence at bottom across that smaller round area near the center. No conductivity on that section or across the rock.

I scrapped it with a screw driver looking for a metal streak but pieces broke off that were dark grey revealing just more dark grey rock.

The dimensions are roughly 1 inch in diameter at the top by 0.75 inch tall by 1.25 inch in diameter at the bottom. The weight is just about at 2 ounces. Sorry, I try and come back and input the metric values later. I need to get the scale out and verify the weight as well.