The Collaborative International Dictionary
Willemite \Wil"lem*ite\, n. [From Willem I., king of the Netherlands.] (Min.) A silicate of zinc, usually occurring massive and of a greenish yellow color, also in reddish crystals (troostite) containing manganese.
Wiktionary
n. (context mineralogy English) A rare mineral, zinc silicate, zinc2siliconoxygen4, that is a minor ore of zinc.
Wikipedia
Willemite is a zinc silicate mineral ( Zn Si O) and a minor ore of zinc. It is highly fluorescent (green) under shortwave ultraviolet light. It occurs in all different colors in daylight, in fibrous masses, solid brown masses ("troostite"), and apple green gemmy masses.
It was discovered in 1830 and named after William I of the Netherlands.
Usage examples of "willemite".
Why, only those rays invisible to the human eye, but which make this piece of willemite glow—the ultraviolet rays.
Why, only those rays invisible to the human eye, but which make this piece of willemite glow - the ultra-violet rays.