Geyserite \Gey"ser*ite\ (g[imac]"z[~e]r*[imac]t or g[imac]"s[~e]r*[imac]t; 277), n. [From {Geyser}.] (Min.) A loose hydrated form of silica, a variety of opal, deposited in concretionary cauliflowerlike masses, around some hot springs and geysers.
Opal \O"pal\, n. [L. opalus: cf. Gr. ?, Skr. upala a rock, stone, precious stone: cf. F. opale.] (Min.) A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity.
Note: The {precious opal} presents a peculiar play of colors of delicate tints, and is highly esteemed as a gem. One kind, with a varied play of color in a reddish ground, is called the {harlequin opal}. The {fire opal} has colors like the red and yellow of flame. {Common opal} has a milky appearance. {Menilite} is a brown impure variety, occurring in concretions at Menilmontant, near Paris. Other varieties are {cacholong}, {girasol}, {hyalite}, and {geyserite}.
Earthquakes, vandalism and a buildup of natural deposits called geyserite all can slow a geyser down.