also: はくうんも
noun
muscovite; white mica
A common light-colored mica mineral. The gloss 'talc' is misleading; muscovite is a different mineral. In Japanese, 白雲母 refers specifically to muscovite, not talc (滑石).
白雲母は火成岩や変成岩によく見られる鉱物です。
Muscovite is a mineral commonly found in igneous and metamorphic rocks.
This rock contains a lot of muscovite.
From 白 (white) + 雲母 (mica). The reading しろうんも is a combination of kun'yomi しろ and on'yomi うんも; はくうんも is pure on'yomi.