I was thrilled to be able to get this site. I was told about it in 2007 by a helicopter pilot but at that time I “poo-pooed” thundereggs, not realizing how amazing they are. I was shocked when I first observed the thundereggs cut open, realizing right away my mistake had always been to break a “ball” open and look for crystals. I won’t make that mistake again! These are beautiful creations of nature. The above specimen is about 5 inches across.
Scientifically, there is still no one model that explains how thundereggs form. Thundereggs Is a “folklore” or “lapidary” name that originated from the Warm Springs Indian tribe in Oregon. It is generally accepted that thundereggs are equivalent to what scientists call lithophysae. Because of the very stretched-out lithophysae that I have recently found (see page on Other Material), I believe that thundereggs form while rhyolitic lavas are still flowing, possibly due to cristobolite forming and releasing gasses.This large, 9 inches across specimen reminds me of Thor from the Marvel world with lightening coming down all around him as he floats down to the ground with hammer raised. I do have the other half.Smaller specimen with darker matrix around 5-point star.Imagine my thrill when I opened up the oil saw cover and saw this beautiful specimen staring at me! It is 9 inches across.Another beautiful 5-point star with common opal fill. This one clearly shows a possible seed sperulite that many have led to the formation of the star.A really nice box or butterfly thunderegg with opal and agate fill. A few specimens show nice green celadonite fill like this little box or butterfly specimen. My mom would have loved these as she adored butterflies.Larger 8 inches long (bigger piece) opal-filled thunderegg, naturally cracked open.A 6 inches across star.A real beauty at 6 inches across and celadonite-filled. I managed to cut this one about perfect for one stellar half. I have cleaned it since but do not yet have an updated photo.The way to read a thunderegg. The green lines mark the pressure ridges, which can tell you what is inside a thunderegg. The one on the left shows the window (green circle) and 5 ridges, indicating a star. The other has 4 ridges indicating a box or butterfly.
