Polished Black Chert Nodule Tan Chalcedony Cortex 1.11 kg — Lapidary Specimen Display Piece Collector

This polished black chert nodule weighs 1.1 lbs (approximately 1.11 kg) and presents a striking natural contrast between its opaque jet-black chert interior and a warm, patterned chalcedony outer cortex banded in tan, cream, and grey. The color boundary zones are sharp and well-defined, giving the piece an almost sculptural quality.

Chert is a microcrystalline to cryptocrystalline silica rock formed in sedimentary environments. The chalcedony cortex — a fibrous variety of quartz — developed as silica-rich fluids migrated through the outer rind of the nodule over geological time. The result is a naturally occurring two-tone specimen that requires no enhancement beyond the polish itself.

The high-gloss lapidary polish was applied to maximize visual impact, pulling out the natural banding and luster of both the chert core and chalcedony skin. This finish makes the piece well-suited for display collections, lapidary study, or use as a reference specimen for understanding cortex formation in siliceous nodules.

Mid-grade collector specimen. One piece available. What you see is what you ship.