5.3" Polished Pilbara Agate Slab - Australia
This is a banded agate slab from a location near Nullagine in Western Australia. The agates are found in the Maddina Basalt and studies have shown that these are probably the oldest agates in the world, with an age in excess of 2 billion years. This colorful slab has been polished to a mirror-like finish on one side and comes with a display stand.
Agate is a variety of microcrystalline quartz that displays translucence and in some cases banding. Agate primarily forms when silica-rich fluids fill pockets within rock and/or fossils, resulting in deposition of the silica along the walls of the rock. This process can result in banding patterns as the composition and impurities of the fluids change over time. These banding patterns can either form as flat layers or rounded layers, depending on the surfaces available for deposition.