Spencer Opal Geodes

Just north east of Spenser Idaho [just north east of Dubois on I15] was the most exciting opal mine I ever had the pleasure of digging in. It was owned and operated by Mark Stattler back in the 'sixties. A volcanic "pitch stone" melt [coarse obsidian] that contained enough H2O to produce geodes. Some time later, Alkali in the area helped hot springs to disolve silica that was later deposited in the geode cavities. Usually only the bottom part of the cavity filled with opal, but the conditions were just right for layer after layer to form very regular layers of cristobalite/trydimite spheres in a diffraction grating that produces brilliant amazing fire patterns.

Silica Information Silica Structure Geodes Geode Sections Exploded View Naked Geodes Geodes in Matrix Geode Formation Geode Couples Spenser Opal Geode Secret Lives My Home Page

Front side of geodes showing fire

Back side of geodes

Close up view of small Spencer Opal geode.