Polished Sardonyx Banded River Agate Stone. Approximately 92 grams. Agate is found in a variety of colors. The material shows intricate natural banded patterns with a variety of colors with hues of red, orange, yellow, white, and black. This aesthetic stone is carved from an amazing find of Sardonyx from a river basin near- Madagascar. Originally known as Banded River Agate or Mad River Agate, the material was recently discovered to actually be Sardonyx, formed from bands of chalcedony in alternating colors. The palm stone is polished for a smooth finish.