210516B

210516B
Caption: Chalk dust (anti-dust type) from a school chalk board / eraser. Chalk (also known as calcite) isa white, porous sedimentary rock. It is a form of limestone that is chemically called calcium carbonate (CaCO3). Limestone forms in deep marine environments from the slow accumulation of very small calcite plates (coccoliths) produced by certain types of microorganisms called coccolithophorids. The famous White Cliffs of Dover are an example of a natural limestone deposit.
Magnification*: x2,135
Type: SEM
Copyright 2010 Dennis Kunkel Microscopy, Inc.
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