These agates are purchased since the early 1980ies. The finding location is located by B. Cross and J. Culp Zeitner in “Geodes, Nature Treasures” (2006) as Tręs Pinheiros, Fountoura Xavier, Rio Grande do Sul. They occur in red soil as remains of a wheathered vulkanite.
These drop-shaped geodes are desired for the contained Quarz-crystallizations inside the nodule. But the agate-collectors are looking for the three different chalcedony-formations inside, wich may appear at the same time:
1. flame- or cloud-agate in reddish or greyish-black colours.
2. banded fortification-agate