Rare & Strange: Silver Dollar

I don't know the full history of this coin apart from the fact that's its a 1922 American silver dollar - with only 35,401 ever minted its very rare.

My brother and I received it in Ireland in 1983 from 'a man in a pub' - an acquaintance of my father. 

The strange thing, which probably devalues this coin down to its bullion value, is the fact it's only one half of the coin!

Looking more closely, it appears to have been 'sliced' in half and presumably mounted as some sort of ornament, going by the big dollop of glue on the back.

Here's what we should see on the back -->

I sent details of the coin to Heritage Auctions as part of their free valuation service. 
Let's see what they come up with.