Difference between revisions of "Black crust"
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== Description == | == Description == | ||
| − | A dark, thin crust that forms on the surface of outdoor [ | + | 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 == | == Synonyms and Related Terms == | ||
Latest revision as of 13:40, 8 January 2014
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.)