Subject: What are some tests to prove that a compound is Calcium Carbonate?

For my chemistry independent study our whole class is given a 
little vile of an unknown salt (ionic compound).  First we do 
qualitative tests by following a flow chart but then we have do 
quantitative tests to prove that our compound is what we say it 
is.  I'm wondering if you have any ideas or specific test I 
could do to prove that I have Calcium Carbonate.  I've tried an 
enthalpy test but that didn't work well, I can't do a pH test 
because Calcium CArbonate is practically insoluble in water.  Basically, I 
need tests that can specifically prove that I have calcium carboante.  Or 
I can do an experiment and compare my results to that of known or expected 
results of CaCO3  If you have any suggestions please let me know.  Thanks, 
Brendan 

Re: What are some tests to prove that a compound is Calcium Carbonate?