This is 1/2 of a thunderegg with blue, gold and smoky black agate as well as peach colored opal. Found this beauty at base of the Mutton Mountains (off road) on the Warm Springs Indian Reservation. Lightly polished.

Weight: 6.9 oz
Size: 3 5/8" wide x 2" tall x up to 1 1/4" deep

Mutton Mountain (half) Thunderegg