sillimanite[sil′ə mə nīt′]
a very hard, mineral, aluminum silicate, AlSiO, usually found in metamorphic rock as long, slender crystals of various colors
Origin of sillimaniteafter B. Silliman (1779-1864), United States chemist and geologist + -ite
A usually white, hard mineral, Al2SiO5, occurring in highly metamorphosed rock as long, slender, fibrous crystals. Also called fibrolite.
Origin of sillimaniteAfter Benjamin Silliman.
(countable and uncountable, plural sillimanites)