OPALITE
Opalite
is an opal-dominated rock (opal = amorphous hydrous silica = SiO2·nH2O).
ÒOpalÓ is a mineral/mineraloid name. ÒOpaliteÓ is a rock name.
Opalites form principally by alteration of volcanic rock or alteration of
siliceous sinter (a type of hot spring deposit). They are often described
as ÒimpureÓ opal rocks. They lack the famous ÒfireÓ & rainbow colors
of gem-grade opal.
The opalite shown below comes from the B and B Mine in
Nevada's mercury belt, western Esmeralda County, southwestern Nevada,
USA. The disseminated reddish material is cinnabar (HgS - mercury
sulfide).
Opalite
(field of view ~3.2 cm across) with cinnabar (= disseminated reddish) from a
paleo-hot spring deposit in Nevada, USA.