calcareous sinter; travertine
A mineralogical term for a porous, banded limestone deposited by mineral springs, especially hot springs. Often encountered in geology or onsen contexts.
At this hot spring area, you can see beautiful terraces of travertine.
鍾乳石 are stalactites formed in caves, whereas 石灰華 is typically deposited around hot springs or mineral springs.
From 石灰 (lime, calcium carbonate) and 華 (flower, here meaning a deposit or bloom), referring to the flower-like or layered appearance of the mineral deposit.