Investigation of the occurrence of a unique efflorescence salt on calcarious museum items

Fibrous crystals, consisting principally of calcium, acetate, chloride and nitrate ions on a number of calcareous museum artifacts worldwide, have been examined. Ion chromatography (IC) was used to determine the exact composition of the efflorescence and nuclear magnetic resonance spectrometry (NMR) was used to determine the degree of hydration associated with the salt. Of the twelve samples analysed, eleven salts had the same stoichiometry as Efflorescence X, a novel salt identified from an Egyptian limestone relief sculpture in the Burrell Collection, Glasgow, that has the composition Ca3(CH3,COO)3 Cl(NO3)2 · 7H2O.