This specimen presents a complete cross-section of a Quartz geode. The open portal, rare in geode specimens, allows light to pass through the piece, casting prismatic refractions from the quartz crystals that line the interior circumference.
The specimen's structure tells a complete geological story. The polished outer rim reveals the dark grey-green Agate that formed the geode's initial shell. This banded chalcedony transitions inward to a zone of white crystalline quartz before giving way to the transparent points that project into the central void. The hollow centre indicates that silica-rich fluids were exhausted before the cavity could fully close, leaving this dramatic aperture.
Brazilian Quartz geodes of this configuration, sometimes called "window" or "portal" geodes, are significantly less common than their fully crystallised counterparts. The preservation of a clean, unobstructed opening while maintaining structural integrity requires precise conditions during formation and careful extraction from the host basalt.
The crystal quality displayed here is exceptional. Glassy terminations with minimal cloudiness and excellent transparency.
Mounted on a custom black stand.
