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A hard, compact layer of a dissimilar material tightly held to the underlying substrate. The term is most often used in reference to a mineral layer with a different color and surface morphology than the underlying stone been formed from minerals migrating from within the stone itself onto the surface.

A bronze Roman serving bowl showing discoloration from mineral encrustation

Related Terms

accretion; crust; concretion

Synonyms in English



English encrustation
French encroûtement
Portuguese incrustação


Encrustations can form on the surface of ceramics, stone, and metal, especially in outdoor and archaeological contexts. They are typically the product of mineral or insoluble salt deposits resulting from the breakdown of rocks or components of the underlying artifact, structure, or associated structures (Cronyn 1990, Buys & Oakley 1996). They are often made of carbonates, sulfates, silicates, or metallic oxides and are usually hard and well adhered to the surface (Cronyn 1990, Vergès-Belmin 2008). Encrustations formed in marine environments may take the form of marine exoskeletons and as iron corrosion products in iron-rich soil environments (Buys & Oakley 1996). Their formation on buildings is often linked to water movement across masonry surfaces (Vergès-Belmin 2008).


Buys, S. and V. Oakley. 1996. Conservation and Restoration of Ceramics. Butterworth - Heinemann, Oxford, 25.

Cronyn, J. M. 1990. The elements of archaeological conservation. London: Routledge, 23, 30 - 105.

Vergès-Belmin, V., ed. 2008. Illustrated glossary on stone deterioration patterns. English-French ed., Monuments & Sites no. 15. Paris: ICOMOS and (ISCS) International Scientific Committee for Stone, 50. http://www.icomos.org/publications/monuments_and_sites/15/pdf/Monuments_and_Sites_15_ISCS_Glossary_Stone.pdf

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