BIOLOGICAL ORIGIN OF MAJOR CHEMICAL DISTURBANCES ON ECCLESIASTICAL ARCHITECTURE STUDIED BY FOURIER-TRANSFORM RAMAN-SPECTROSCOPY

Lichens, formerly considered as weathering agents in a geological cont ext, are shown to be capable of biodeteriorating stone substrata withi n a relatively short time-scale. Detailed Raman spectroscopic studies have demonstrated the highly destructive properties of calcium oxalate produced by lichen thalli. Dirina massiliensis forma sorediata is cap able of chemically disturbing substrata to depths of almost 2 mm in un der 12 years and converting the substrata into substantial quantities of calcium oxalate. Studies of disfigurement of English church walls a ssumed to have been rendered with a decorative or protective surface v ia restoration, have also been proved spectroscopically to be the resu lt of this lichen's biodeteriorative action. (C) 1997 John Wiley & Son s, Ltd.