Polka dot agate sphere Agate a variety of quartz

a variety of quartz

Material is from the Oregon/Nevada border

The intricate banding pattern is formed by the gradual deposition of these minerals in alternating layers within gas-filled cavities in volcanic rocks

African amethyst refers to amethyst gemstones

Polka dot agate sphere Agate a variety of quartzPolka Dot agate sphere. 3. 25" (approximately) or 82mm Material comes from Oregon Polka Dot Agate is so named for it's polka dot pattern. The dots in the agate range in size from very tiny up to about 1 4 inch across. Most of them are completely agatized, but some appear to be a soft iron oxide material similar to limonite or hematite. Most of the dots are sharp, concentric spheres.