Iowa Keokuk Geodes
Digging on the countryside in Iowa for eight hours yielded nearly three pails of geodes ranging from tiny golf ball to baseball sized rocks pulled from damp shale layers. It didn't take too long to get through overburden and into pockets of preserved geodes like the calcite example shown here. Patience definitely came in handy while digging as we were told to watch carefully for fossil specimens rarely found between the layers. This trip didn't uncover any of those sought after plant and coral fossils, but we did manage to find many beautiful geodes embedded in the hillside.
Most of the geodes revealed sparkling white or clear calcite crystals when split apart with a hammer pick. A handful of specimens featured yellow, brown, and orange coloring in the calcite which certainly grabbed our attention. Two of the geodes contained rather dark brown dolomite crystalline structures mixed with calcite. Overall, many of the rocks were pretty easy to open along cracks and fault lines though a few did require the help of a short 10 pound sledge and rock chisel.
Helpful tools for excavating geode clusters from the shale include a small rock pick axe, entrenching shovel, rock chisel, pry bar, small sledge, buckets and one container with water on standby. A soil pipe cutter may prove helpful for opening the stubborn ones. Since digging to the geodes is not a physically intensive process, and with the precision required for removing layers without destroying a potential fossil specimen, smaller tools and patience worked best for us. The water container on standby is to keep any fossil finds moist as they're found to later control the drying process. Exposing the fossil to dry are for too long right away causes it to crumble apart.
The experience is very much worth time and effort involved in locating geode sites then spending a day digging. Seeing first hand how these beautiful crystalline rocks are formed in the natural environment is quite interesting as well, considering many of the clusters show geodes in various stages of formation from a small nickle-sized ball to much larger, much like a bunch of grapes if the grapes varied in size. The prospect of finding rare fossils along with the geodes was certainly intriguing, but the thrill for us was every time a cluster of geodes were found buried in the layers of shale.
