“The color of chalcedony commonly varies from one thin layer to another, producing thin, concentric bands that are the hallmark of the variety agate. I suspect that relatively few agates show rather abrupt color variations longitudinally within bands, as seen here. This chalcedony partially fills what was once a vug within grainy chert matrix, and the inner-most part of that vug was filled by quartz crystals. I wetted this sawed piece for photography because the fractured rock would not have survived polishing. Collected and photographed by Norman King.”