noun
citrine; yellow quartz
Mineralogical term for the yellow variety of quartz, often used as a gemstone.
黄水晶は11月の誕生石の一つです。
Citrine is one of the birthstones for November.
紫水晶 is amethyst (purple quartz), while 黄水晶 is citrine (yellow quartz).
Compound of 黄 (き, 'yellow') + 水晶 (すいしょう, 'crystal/quartz'). The reading きずいしょう follows standard rendaku voicing rules.