Help Me Identify This Rock!

[TreasureNewb]

Hi Everyone!
We just got the OMMO DT-4 metal detector and found these rocks. The metal detector classified it as silver in the 90’s. I broke a smaller one so I could see what it looked like inside. Seemed to be a hard, heavier black with shiny specks throughout.

Anyone know what it is??

 

[Mark ( ohio )]

Looks to be what we call in my area as a hot rock... Its magnetized slag left over from the steel mill days.

Just a guess, but thats what I think it is.