An article about unusual nodules with the mystical name “thunder eggs”. As the Indian legend says, the stones were the eggs of thunderbirds that lived on the tops of the mountains. The spirits of thunder threw them at each other during quarrels - this is how thunder rumbles during a thunderstorm were explained.
This is the romantic name for the nodule, and the mineralogical name is lithophysis.
Lithophyses are spherulites formed in felsic igneous rocks that have undergone some expansion during growth to form voids that are very often filled with silica.
In other words, it is a mineral of complex composition, spherical in shape, formed as a result of volcanic activity.
How they are formed
Lava flows that harden into rocks often contain cavities that are formed during a volcanic eruption. Over time, the water containing the minerals in solution precipitates, forming crystals in the empty spaces.
Quartz and gypsum crystals can often be found here. Thunder eggs are found specifically in rhyolitic lava flows (containing large amounts of silica), formed in bubbles after the precipitation of the silica mineral
Stop for a moment and look at the gallery:
The process of their creation is the result of a long and complex history of changing environmental conditions such as temperature, pressure, depth, magmatic composition, groundwater geochemistry and environment.
Thunder eggs were first discovered in Oregon, Beaver Country, in the United States.
What do geodes have to do with them?
Although they may sometimes look similar, thunder eggs and geodes are not exactly the same. A geode is filled with crystals (often quartz) but contains a cavity inside, while thunder eggs are usually completely filled with minerals.
Geode:
Thunder Egg with Geode Element: A world-famous stone that is named "Cookie Pie" because it resembles a character from the famous show.
And here is the prototype - the Cookie Monster (“Cookie Pie”) from “Sesame Street”.
Thunder eggs and agate are not the same thing. So, the nodules that form thunder eggs can be filled with both agate and chalcedony, opal, and quartz. Look at the examples:
New finds in Oregon. These unique eggs are characterized by a high contrast mixture of very dark matrix and white-blue-gray/pale agate and quartz.
How to detect
Although thunder eggs look like rocks, they are easily recognized by their abnormally rounded and jagged brownish-gray appearance. Typically, thunderstorm eggs lie relatively close to the Earth's surface, embedded in the tuff clay where they formed. Over time, the tuff has turned into soft mud and clay, making them visible
Where to find them
Thunder eggs can be found all over the world. Well-known locations include the US state of Oregon and Germany, as well as Poland, Romania, Ethiopia, Argentina and Canada, among others.
Although they can be found all over the world where conditions are optimal, Oregon is a hot spot for these finds. The world's largest thunder egg, weighing 1,75 tons, was found in this state!
The most amazing cross-section images of thunder eggs are known all over the world, thanks to photographers and the Internet:
- One of the most famous is the Friendly Ghost "Casper", whose face was seen when cutting open a thunder egg.
- And this is a wonderful bird, rhyolite with agate inside was found in Chihuahua, Mexico:
