Thundereggs are geological structures which are similar to geodes. They are formed during volcanic eruptions. If you can visualize lava flowing and just before it hardens you sometimes see it balling into masses and then popping. This is due to the expansion of gasses within and doesnt always happen. Sometimes the gasses remain trapped within the masses and the shell hardens. What takes place then is over millions of years other minerals seep into the void filling them over time. Lots of the time they are filled with Agates but you will also find some with Jasper, Chalcedony as well as Opal cores. The outer shells are mostly comprised of Ryolite. When cut in half and polished they exhibit fabulous patterns and none will ever be the same making them a great collector's item. Thundereggs are not actually rocks but rather are considered to be geological nodules which occur within other Igneous rocks. They range in size from golfballs to larger than basketballs with most being about the size of a baseball. Thundereggs from different locations show distinct characteristics most of the time.. especially in their outer shells.

The most famous Thundereggs come from Oregon and a local native legend states that the thunder spirits lived on the highest reaches of Mount Hood and Mount Jefferson. When they became angry at each other they threw these rocks at each other hence the name Thunderegg. Although not classified as a rock in 1965 the Thunderegg was designated as Oregon's state rock.

Thundereggs are found in other locations with some of the most beautiful coming from the Baker mine in Nevada. Along with this they are also found in Washington state, British Columbia, Haida Gwaii and other areas of North America. Germany, Argentina, France, Poland and Australia along with other counties are also sources. Mount Hay in Australia produces beautiful specimens as well.

Baker Mine. Many consider eggs from this mine to be the most beautiful available. About 20% of the eggs from here contain Quartz pockets and about 5% of that 20% contain Quartz Stalagtites/Stalagmites. Now.... those people who collect and cut thundereggs themselves know from the outside which way to cut these eggs to best show the layering of the agate. (In other words they know what side of the egg is up and down and which sides are the sides) But the cut is still a guess because you never know what/where the inclusions may be and where in the egg the best patterning may be. I have seen quite a few of these eggs with stalagmites but in all of them the cut cut through at least one stalagmite which to me really took away from the appearance of the egg... the eggs just didnt appeal to me. This egg is the first one I have ever seen which was lucky enough to be cut without cutting through a stalagmite.... its quite stunning and I knew I had to have it

Thundereggs hold all the propeties of Agate or the properites of whatever mineral they are made up of. Along with this they make for great energy stones to help create a positive energy for the environ. Scattered throughout the house they not only make for great conversation pieces but also add a protective and grounding energy. They also add a joyous energy to any room.

It seems that Europeans called small roughly polished Mount Hay (Australia) Thundereggs "Amulet Stones". It was their belief that if they were powerful enough to contain and hold the energies of a volcanic eruption they could also store the energies of humans making them ideal for healing or protective amultes