BRECCIATED CHERT FOR SALE

How Does Brecciated Chert Form?

Brecciated chert from Australia—especially from ancient terrains like the Pinyalling Hills—forms through a multi-stage geological process that unfolds over hundreds of millions to billions of years. In the Archean greenstone belts and sedimentary successions of Western Australia, the process typically involves:

1. Original chert formation - The story begins when silica accumulates on the seafloor, often from the remains of microorganisms such as radiolarians or through direct chemical precipitation in ancient oceans. Over time, this silica compacts and lithifies into hard, fine-grained chert.

2. Tectonic fracturing - As the region experiences tectonic stress—common in Archean terranes—the solid chert becomes brittle and fractures. Earthquakes, folding, faulting, and regional metamorphism all contribute to breaking the rock into angular fragments, forming what geologists call a breccia.

3. Silica-rich fluid infiltration - After fracturing, mineral-laden groundwater or hydrothermal fluids seep into the cracks. These fluids often carry dissolved silica, iron oxides, and trace elements.

4. Cementation into a breccia - As the fluids cool or the chemistry changes, the dissolved minerals precipitate, filling the fractures and “gluing” the broken fragments back together. This creates the characteristic jigsaw-like mosaic seen in brecciated chert.

5. Multiple brecciation events (common in Australian terrains) - In many Australian localities, this process repeats more than once. Old fractures may break again, and new mineral cements infill the later cracks. This produces complex, multi-stage breccias with striking patterns.

6. Coloration from iron and trace minerals - Western Australia is rich in iron oxides and other accessory minerals. These permeate the silica during cementation, creating the reds, yellows, ochres, creams, and dark bands that make the stone visually dramatic.