Can you tell us where you found it?
Go look for more.
It looks like a nice piece of silver ore.
Hard to tell just from a pic, but to me it looks like a high grade silver ore in a chalcedony matrix. The bubbled area looks like chalcedony that has been stained by some brownish mineral. It looks like your rock has a crust or rind that would represent the outside edge of the vein.
Interesting enough to take to rock and mineral show for a better evaluation.