Difference between revisions of "Black crust"
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== Synonyms and Related Terms == | == Synonyms and Related Terms == | ||
| − | gypsum crust; black spots; Schwarze Kruste (Deut.); croute noire (Fr.); | + | gypsum crust; black spots; Schwarze Kruste (Deut.); croute noire (Fr.); crosta negra (Port.) |
[[Category:Materials database]] | [[Category:Materials database]] | ||
Revision as of 11:59, 28 August 2013
Description
A dark, thin crust that forms on the surface of outdoor limestone and marble sculpture. Black crust, or gypsum crust, contains airborne particulates (carbon, dirt, salts) deposited on the stone surface. The particulates are held in place by a gypsum layer formed by the reaction of acidic sulfur-containing pollutants with the calcite.
Synonyms and Related Terms
gypsum crust; black spots; Schwarze Kruste (Deut.); croute noire (Fr.); crosta negra (Port.)