Cinder

A Cinder is a fragment of cooled pyroclastic material (lava).

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The following geologic characteristics define a cinder:

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• Uncemented
• Vitric
• Having bubble-like cavities, called vesicles
• Measuring not less than 2.0 millimeters in at least one dimension
• Apparent specific gravity between 1.0 and 2.0

Typical cinders are red or black in color.

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Cinders are popularly employed as inorganic mulch in xeriscaping, because of excellent drainage properties and resistance to erosion. In this context, they are referred to frequently with the colloquialism "lava rock".

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