Quote:
...if so please remove to a more apropriate place.
Done.

For the coin, I would read the mintmark as "R", rather than "B". Not that that makes any difference to what the coin "should" weigh.
There are two possible reasons why your coin weighs only half of what it should weigh, and be so severely pitted:
(1) the coin is a counterfeit.
(2) the coin has been severely corroded (by acid or other means).
I think acid corrosion would be more uniform, so I would tend to go for the counterfeit theory.
Quote:
Though usually crude and carelessly engraved, some counterfeits are of decent workmanship, and entirely undistinguishable from government issues. Brazilian collectors generally accept these contemporary counterfeits as collectable, due to their historical value.
I have always been amused by these lines quoted from Krause. To put it in other words: "Counterfeit? Who cares?!".
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis