Sieber Agate 10mm Round AA Grade - 15-16 Inch Tree Agate These inclusions give it a

These inclusions give it a glistening effect termed “aventurescence

and delicate detail work

It may also contain rainbow to colored or sparkling inclusions

It is an aluminum borosilicate mixed with iron

It should be cleaned with a damp cloth and avoided from getting wet

Sieber Agate 10mm Round AA Grade - 15-16 Inch Tree Agate These inclusions give it aSieber agate is not a true agate but rather a glassy, dark blue grey or green copper slag that formed during ancient copper smelting in Germany, specifically from the Siebertal area. This historical "ancient slag" has a naturally swirling, intricate appearance resembling agate due to silica and mineral inclusions from the smelting process. It is a rare and collectible material known for its lapidary qualities, similar to obsidian, and is sometimes