9.4" Agate Slice on Metal Base - Brazil

This is a gorgeous slice of agate from Brazil. It has been cut and polished on both sides revealing the exciting banded patterns. The agate features white, gray, and blue chalcedony bands throughout the specimen.

This nodule sits snuggly on a custom metal display stand that is not removable. A hole has been drilled into the underside of the slab and the metal pole has been inserted and glued into aforementioned hole.

Agate is a translucent variety of microcrystalline quartz. 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.

Agate has also been known to fill veins or cracks in volcanic rock. Such agates, when cut transversely, exhibit a succession of parallel line giving a banded appearance to the section. Such stones are known as banded agate, riband agate and striped agate.

The agates from Brazil are mined from decomposed volcanic ash and basalt from the late Permian age (248-275 million years old) In Rio Grande do Sul the "agate mines" are normally just plowed fields in which loose agates are found and collected. These agates can be very colorful and polish beautifully.
Chalcedony var. Agate
9.4 x 8.3" (without base), about .95" thick, 12.9" tall on stand