The Miyaneh Thunder's Eggs

What we named “Miyaneh thunder’s eggfield” here is a group of T.E fields those located in southeast Miyaneh city and about 20 to 30 km far from it. This area covered the volcanic outcrops near villages Giz Galasi, Ghaleh Sang, Mavi, Vahil-gavani and Eskough which named Ghaflan Kuh area in general.  The prominent geological phenomenon of this mountainous area is a vast volcanic rocks which form all eminences of area. These volcanic rocks are a thick sequences of lava & tuff layers which are mostly massive and rhyolith to rhyodacite and trachyte in composition. Some perlite and pumice sparse layers could be seen in the area. All above introduce an acidic volcanic activity which happened during Oligo-Miocene. This extensive volcanic state is mostly weathered on surface.

Thunder’s eggs found as loose nodules in different sizes which scattered on surface of mounds. Nodules are between 3 to more than 30 cm in diameter and are mostly spherical to ellipsoidal in shape. The outer skin of them show the famous “turtle’s back” structure which is common in T.Es. This thunder’s eggs are mostly fill with blue to pale blue chalcedony with liesegang banding and in some cases geode structure. But “ water level “ thunder’s egg with their well-known horizontally bands has not been reported.    

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