noun
realgar
Mineralogy term for the arsenic sulfide mineral realgar, often found in low-temperature hydrothermal veins.
鶏冠石はヒ素の鉱石鉱物の一つである。
Realgar is one of the arsenic ore minerals.
雄黄 (orpiment) is another arsenic sulfide mineral, often associated with realgar but with a different crystal structure and color.
The kanji 鶏冠 (cockscomb) refers to the mineral's red-orange color resembling a rooster's comb, and 石 means stone. The exact historical derivation is uncertain.