Quote Originally Posted by gillianreynolds View Post
calcium carbonate from oyster shells and just pure carbonate calcium ( I have seen on bottles of calcium) are the same or different. I am a little confused. I have always assumed that if the calcium is from oyster shells the lable says so. But now I am not sure. if the bottle says carbonate does that mean its from oyster shells.
Oyster shell is just one possible source of calcium carbonate. For example, egg shells are also composed of calcium carbonate. Calcium carbonate can also be made chemically. Therefore, if it says it is specifically from oyster shells then it should be. If not, there may be another source.

Susan