Keokuk Geode with White Band
This specimen is highlighted by a very thin band of what I take to be white agate. Only a superficial resemblance to a thunderegg but still - anything that seems to classify into 'inner' and 'outer' could be mistaken under some circumstances.
10cm
Countries:
USA - Canada - Alaska - Mexico - Argentina - Peru - France - Germany - UK - Poland - Greece - Turkey - Romania - Bulgaria - Slovakia - Kazakhstan - Uzbekistan - Russia - Japan - Ethiopia - Iran - Australia - Unknown