captfred,
No one 'keeps' anhydrous copper sulphate - you make it! Heat hydrated copper sulphate gently to remove the water. It will change from blue to white - if it goes brown, you heated it too strongly. Goes from white back to blue when it re-absorbs water of crystallisation.
Copper sulphate, which used to be in all the chemistry kits umpteen years ago, is now on the list of nasties - poisonous if you ingest it.
Regards, RAB