Dumortierites

Part of speech: noun

Definitions

1. A type of blue or green metamorphic rock characterized by its unique mineral composition, often containing dumortierite, quartz, and other minerals
2. A distinct variety of rock known for its striking colors and patterns, primarily comprising the mineral dumortierite along with various other materials
3. A geological formation that features abundant dumortierite, notable for its aesthetic appeal and use in decorative stone applications

Etymology: Dumortierites is the plural of dumortierite, so the word names more than one specimen or variety of the mineral. The mineral itself was named after Eugene Dumortier (1803-1873), a French palaeontologist, and the "-ite" ending is the standard suffix used for minerals and rocks, derived from the Greek "-ites" meaning "belonging to." The surprise here is that the name honours a fossil expert rather than a mineralogist. Dumortier's name was attached to a blue aluminium borosilicate mineral, the sort of mineral the rock's composition is built around, so the ending was simply added to his surname as a tribute. Note that the definition given with this entry describes a metamorphic rock, while dumortierite is itself a mineral, so the rock is named for it rather than the other way round.