Unidentified Metal- please help

That looks similiar, but Galena is 2.5 to 2.75 on the Mohs Hardness scale and this is atleast a 4.5 to 5. I cant scratch it with a knife blade unless I use alot of force or hit it with it, then it will leave a scratch. And there are no crystal structures on any of the "rocks" Ive found. I now all specimens of Galena probly wont have the crystal structure, but I have 7 to 8 good size pieces and they all look pretty much the same.

The outer part that looks like oxidation streaks dark grey/ black, but the inside silver part streaks silver, but is easily brushed off the ceramic to where theres no mark at all it looks like, whereas the outer part that streaks blackish grey it doesnt easily come off the uncoated ceramic.