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Webster 1913 Edition
Xylanthrax
Xy-lan′thrax
,Noun.
 [Gr. 
ξύλον 
wood + ἄνθραξ 
coal.] Wood coal, or charcoal; – so called in distinction from mineral coal. 
Definition 2025
xylanthrax
xylanthrax
English
Noun
xylanthrax (uncountable)
-  (archaic) Wood coal or charcoal, distinguished from mineral coal; lignite.
-  1821, Journal of the Academy of Natural Sciences of Philadelphia: Volume 2 (page 24)
- This clay formation, entirely unconnected with that of the Mississippi, and the lower part of the Arkansa, is of a blueish-grey, abounding in pyrites and xylanthrax, and is the active seat of those pseudo-volcanoes and their remains existing in the upper part of the Missouri territory.
 
-  1863, The journal of the British Archaeological Association: Volume 19 (page 321)
- There are two beads of much interest: a small cylindrical one of chrysoprase, and a large one turned out of a piece of xylanthrax, similar to that met with at Bovy, Devonshire.
 
 
-  1821, Journal of the Academy of Natural Sciences of Philadelphia: Volume 2 (page 24)