Cinders

n. ash, ember, small piece of burnt wood or coal

Disambiguation: for the Killer Instinct character, see Cinder (Killer Instinct). For the post-rock band see Cinder. A cinder is a fragment of cooled pyroclastic material (lava or magma). Cinders are either intrusive igneous (magma cooled inside the earth) or extrusive igneous (lava cooled outside of the earth). Cinders are similar to pumice, which has so many cavities and is such low-density that it can float on water.  Pumice or cinders are used in soap, xeriscaping, mulch, and rock gardens.
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Noun
1. a fragment of incombustible matter left after a wood or coal or charcoal fire
(synonym) clinker
(hypernym) fragment

Glassy, porous, pyroclastic rock fragments.

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