Cleure unscented spray deodorant does contain potassium alum, or potassium aluminum sulfate. This is a naturally occurring mineral found on rocks that contain sulfide and potassium minerals. This natural mineral salt is made up of molecules that are not absorbed by your skin, due to their large size. They inhibit the growth of odor-causing bacteria by forming a protective layer over your skin. It is found in many foods and in the human body.