Webster's Revised Unabridged Dictionary · 1913

Geyserite

Geyserite (gī"zẽr*īt or gī"sẽr*īt; 277) , noun

[From Geyser.]

(Mineralogy) A loose hydrated form of silica, a variety of opal, deposited in concretionary cauliflowerlike masses, around some hot springs and geysers.