Black Chalcedony with Pink Stilbite

Black Chalcedony often forms in rhyolite, basalt, and andesite flows, where silica-rich solutions infiltrate gas bubbles or fractures in volcanic rocks.

• Can also occur in marine sedimentary environments as nodules or concretions (similar to flint or chert).

• The black coloration is due to inclusions of organic matter, iron oxides, manganese, carbon, or other dark mineral impurities.

• These inclusions are dispersed microscopically through the quartz matrix, giving a uniform dark appearance.