Well, if I'm figuring this right, if that were lead, it would weigh something like 85-90 pounds.
Your dimensions come out to 220 cubic inches. Lead weighs 0.39 pounds (6.24 ounces) per cubic inch.
That's at least 85 pounds.
Could be Vanadium or Gallium.
Actually, it literally COULD be vanadium, in theory. It matches your description on weight estimates per cubic inch.