Three pictures. All taken with a flash.
The rock is very dark (black) with metallic colored streaks/small patches.
It weighs 350 grams.
I’ve measured its volume (via imprecise water displacement) at between 50-55 cm3^3. So its density is probably between 6 and 7 g/cm^3.
There are a couple faces that appear to have been formed by pieces of the rock breaking off relatively recently in its history. The second picture shows one of those. These faces contain many tiny metallic/sparkly pieces and are lighter in color (grey, not black).
Refrigerator magnets do not stick to it.
I found it over ten years ago in western Pennsylvania, specifically a park in New Kensington. It was sitting on grass next to disturbed soil. I remember thinking that either someone had dug it out and left it or it was kicked up by a lawn mower.
Alcoa had facilities in New Kensington going back over a hundred years. Between that and the possibility of industrial byproducts from other random ventures being scattered wherever, I’ve always assumed that something related to that is the most likely source of this rock.