Cannot find the degradation temp. of Calcium Carbonate?

Question

I am trying to come up with the temperature at which aragonite, a polymorph of calcium carbonate breaks down.
None of the tables in my books seem to have this available.
Thank you!

Answer 1

When Calcium carbonate is heated to decomposition (825° C), it emits calcium oxide fumes and liberates carbon dioxide.

Aragonite is similar in thermal decomposition. (see the second site).