Agate tumble

Size: about 20mm-36mm

The banding in agate is based on periodic changes in the translucency of the agate substance. Layers appear darker when they are more translucent (this may appear reversed in transmitted light). This effect may be accompanied and amplified by changes in the color of neighboring layers, due to other co-precipitated minerals. In old agates that have been subject to weathering and chemical alteration the differences in translucency may disappear, such specimens may turn almost opaque.