geyserite

noun

opal variety found deposited at orifices of geysers

Wiktionary

noun

Etymology: Etymology tree English geyser Proto-Indo-European *-tósder. Ancient Greek -της (-tēs)der. Ancient Greek -ῑ́της (-ī́tēs)der. Latin -ītēsbor. French -iteder. English -ite English geyserite From geyser + -ite.

A type of stone, a mixture of quartz and opal deposited by a geyser as it precipitates out of the boiling water.