Tourmaline
WordNet
noun
(1) A mineral that is a complex borosilicate and hydroxide of aluminum containing iron and magnesium and calcium and lithium and sodium; it is usually black but occurs in transparent colored forms that are used as gemstones
WiktionaryText
Etymology
Either directly from Sinhalese tóramalli 'carnelian', or via one of the cognates German Turmalin, Portuguese tormalina, French tourmaline
Noun
- A complex black or dark coloured borosilicate mineral
- A transparent gemstone cut from it