Difference between revisions of "Chalk"
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(New page: Chalk is a white, Sedimentary rock, composed of calcite. When chalk is formed naturally on a hill, it is called downland. Nowadays, chalk has been replaced by other substances. For exampl...) |
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Revision as of 15:04, June 23, 2007
Chalk is a white, Sedimentary rock, composed of calcite. When chalk is formed naturally on a hill, it is called downland.
Nowadays, chalk has been replaced by other substances. For example, the "chalk" that is used in blackboard writing or in sidewalk chalk is actually gypsum.