Bark for basking site?

[roguemako]

I have collected some pieces of bark and wanted to know if these would be safe to use for basking sites if I boil the pieces in boiling water first... are they?

 

[roguemako]

I collected them from the wild I should mention

 

[evut]

This article might help.
If you're not sure, you can buy cork bark from pet shops - it is quite cheap over here.