Old English, from Medieval Latin, from Arabic رَهْج اَلْغَار (rahj al-ḡār, “cave dust”).
realgar (usually uncountable, plural realgars)
- (mineralogy) A mineral, arsenic sulfide (AsS), often associated with orpiment and stibnite in lead, silver and gold ores.
- “Realgar” in David Barthelmy, Webmineral Mineralogy Database, 1997–.
- realgar mindat.org, Hudson Institute of Mineralogy, accessed 29 August 2016