104
ditional presence of metavivianite (a polymorph of vivianite) was indicated by
this analysis.- Richter, E. L. 1988. Seltene pigmente im Mittelalter. Zietschrift Jur Kunsttechnologie
und Konservierung 2 (1):171-77. - J. Darrah. 1987. Personal communication. Victoria & Albert Museum, London.
- Mineral deposits are found in England, France, Germany, Italy, Portugal, Serbia,
and the Ukraine, as well as in the United States and elsewhere. I am grateful to
Mr. Peter Tandy of the Natural History Museum, London for providing this
information and for guiding me through the extensive range of samples in the
collection. I am also indebted to Dr. Brian Young of the British Archaeological
Survey for his enthusiastic interest and informed opinion on the provenance of
the mineral. - Watson, T. L. 1918. The color change in vivianite and its effect on the optical
properties. The American Mineralogist 3 (8): 15 9-61. - P. Tandy. 1994. Personal corrununication. Natural History Museum, London.
- Following initial exposure of the colourless mineral, oxidation of one of the
paired ferrous ions may occur at the surface and along crystal cleavages. The
resulting intervalency charge transfer between the paired ions (now Fe2+ and
Fe3+) produces a blue color. Cressey, G. 1994. Personal communication. Natural
History Museum, London. - Hanzel, D., W Meisel, 0. Hanzel, and P. Glitlich. 1990. Mossbauer effect study
of the oxidation of vivianite. Solid State Communications 76 (3):307-10. - This information was kindly provided by Mr. David Perry and published by
Park, op. cit. - Oakeshott, W. 1981. The paintings of the Holy Sepulchre Chapel. Winchester
Cathedral Record 50, plate 98a. - Welford, P. 1991. Investigation of the phenomenon of dark flesh areas in English
medieval wall painting. Diploma diss. London: Conservation of Wall Painting
Department, Courtauld Institute of Art, University of London.
Historical Painting Techniques, Materials, and Studio Practice