By Living Room Realty, February 14, 2020
No, it’s not the name of Portland’s trendiest new brunch spot, the Thunder Egg is Oregon’s state rock!
A thunder egg is a rock similar to a geode, that is formed within rhyolitic volcanic ash layers. They are spherical in shape and can range in size from a centimeter to over a meter across! They can contain a myriad of crystals inside, including chalcedony, agate, jasper, opal, quartz, and gypsum.
Thunder eggs were formed thousands of years ago in rhyolite lava flows, when tuffs within the gas or steam pockets served as molds within the lava. Typically, the cavity was filled with silica-rich fluids that later solidified and crystallized. Mineral impurities collected in bands, creating the concentric colorful rings you see in thunder eggs today.
Thunder eggs are found in regions of Central and Easter Oregon. To get a thunder egg here in Portland, check out Ed’s House of Gems in the Roseway neighborhood.
