Oregon Thunderegg Split
The Blue Mountains of Northeastern Oregon hold a variety of dominant geologic features such as the extensive and voluminous Columbia River basalt flows. In a specific locality, the underlying series of Early Tertiary (65 to 60 million-year-old) rhyolitic volcanic flows have been exposed, yielding exceptional thundereggs. These spherical masses, normally ranging in size from less than an inch to four feet in diameter, are typically the size of a baseball. When halved and polished, they may reveal exquisite, colorful patterns.
The present offering a complete thunderegg, which has been split into two halves is an excellent example of its type. Calcite has filled the void between the multi-colored rhyolitic jaspers. (2) Each half measures approximately 13 1/4 x 12 1/2 x 5 1/2 in