Oregon Thundereggs are nodule-like masses usually formed within a rhyolitic lava flow. Silicates such as agate and opal along with other minerals filled pockets in the rhyloite creating egg shaped nodules. Most of the so called eggs are fairly plain banded gemstone. But on occasion other minerals and or crystal structures made for very interesting gemstones.This stone is from the Lucky Strike deposit. The bright camera lights or sun light, bring out it's bright colors. The pendant is 29x22mm (1.15" x .90") Chain not included.