Around Burns several well-known places of discovery for Thundereggs (e.g. Secret Ridge, Harper red bed ( Skull Springs) among others) are situated, in addition, beside these are again and again strewing finds in the region possible. One type are “thunderegg cores”, i.e. the agate centers of Thundereggs - without the Lithophyse originally surrounding it. Interesting is also the occurrence of Obsidian, which contains small Thundereggs as inclusions. By them one can recognize substantial formations of Lithophysae: They need a strongly silicic acid-rich environment, from which they can crystallize then spheruliticaly - the hostrock remains glasslike (or has a respectable high glass portion.).