Sure it's a cool rock. Anything worth taking home is a cool rock, we've got a yard full of them but I think the coin might be worth more to some people. My guess it's a piece of Magnetite that's very well water worn. Have you seen that ironstone jewellery?
On the other hand the texture looks like a blue rock we brought back from Wittenoom in WA. My mind is blank at the moment but I'll remember it soon
My guess is black jasper. Again, this is a guess. Recently tumbled a piece that looks identical, it's jet black and will shine up amazingly.
Moneybox, why would you feel the need to make the comment that some people might find the 50 cents more valuable? The bloke is simply after a simple rock identification he doesn't think it's a piece of gold
Mackka, Leverite? Do you mean 'Leaverite?' as in the geologists 'joke'?...
Moneybox, this looks nothing like Riebekerite. How do u possibly came to that conclusion is baffling. It's also not magnetite and looks nothing like it.
Cackyz, my suggestion if you want serious answers, from real rockhounds, a rock identification page on reddit or Aussie lapidary forum will be more helpful than here.