7" Polished Chert Breccia Slab - Western Australia

This is a slab of chert breccia, collected from the Pinyalling Hills in the midwest region of Western Australia. One side has been polished to a mirror like finish. Chert breccia consists of innumerable angular fragments of assorted rock types. The dominant rock types associated in the mix are quartz, jasper and chert.

It comes with an acrylic display stand.

Quartz is the name given to silicon dioxide (SiO2) and is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich environments--usually igneous rocks or hydrothermal environments like geothermal waters--at temperatures between 100°C and 450°C, and usually under very high pressure. In either case, crystals will precipitate as temperatures cool, just as ice gradually forms when water freezes. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountain formation: these veins can be hundreds of millions of years old.

Jasper is a term that can be applied to an opaque variety of chalcedony. The opaqueness is due to a higher concentration of impurities mixed with silica/quartz compared to other varieties of silica, such as quartz or agates. Like agate it may form in a wide variety of colors, and is often multi-colored. In most cases, jasper forms when silica-rich fluids permeate throughout a soft sediment or volcanic debris deposit. The fluids then crystallize around the particles/impurities, resulting in a cementation process. Most often, the impurities present determine the coloration of the deposit following solidification, but other factors can play a role in the color of what is now considered a jasper.

Jasper, Quartz & Chert
Pinyalling Hills, Western Australia
7 x 4.2", .9" thick