neptunite
/ˈnɛptjuːnʌɪt/ /ˈnɛptʃuːnʌɪt/Mineralogy
noun
A monoclinic silicate of sodium, potassium, lithium, ferrous iron, manganese, and titanium, usually occurring as black prismatic crystals.
Origin
Late 19th century; earliest use found in Mineralogy Magazine. From Neptune + -ite, after Swedish neptunit, so called because of its occurrence with aegirine, Aegir being the name of the sea-god in Scandinavian mythology.