CHIASTOLITE
Etymology
Noun
chiastolite (countable and uncountable, plural chiastolites)
(mineral) An aluminosilicate mineral having carbon inclusions, a variety of andalusite.
Synonyms
• macle
Source: Wiktionary
Chi*as"to*lite, n. Etym: [Gr. -lite. See Chiasm. So called from the
resemblance of the cross cuts of is crystals to the Greek letter x.]
(Min.)
Definition: A variety of andalusite; -- called also macle. The tesselated
apperance of a cross section is due to the symmetrical arrangement of
impurities in the crystal.
Source: Webster’s Unabridged Dictionary 1913 Edition