Abstract: A method for separating membrane from an avian eggshell comprising the steps of providing pieces of egg shell having attached membrane, contacting the pieces of egg shell having attached membrane with a carbonic anhydrase enzyme or an acidic aqueous medium, applying physical force to the pieces of egg shell having attached membrane, and separating the pieces of egg shell from the detached membrane. A method of producing purified calcium carbonate comprising the steps of; providing impure calcium carbonate material, contacting the impure calcium carbonate material with an aqueous acid to produce carbon dioxide and an aqueous product mixture comprising a calcium salt, adding an aqueous base to the aqueous product mixture, adding a carbonate source to the aqueous product mixture to produce calcium carbonate and a salt by-product, and precipitating purified calcium carbonate.