An efflorescent salt found on excavated limestones that have been stored or displayed in the presence of acetic acid vapor. Thecotrichite is composed of calcium acetate nitrate chloride hydrate. It is only formed under very specific conditions in which a calcareous stone that contains chloride and nitrate ions is put in an environment with acetic acid vapors and moisture. Mitigation involves any or all of the following: 1) desalination, 2) decreasing relative humidity, or 3) elimination of acetic acid vapors.
