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The Mineral Identification Key |  |
Concretions
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| Concretion - Calcite "Fairy Stone", Quebec, Canada, 6cm across |
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| Glauconite inclusions in sandy calcite concretion, Wisconsin, 5cm high. |
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| Glauconite inclusions in sandy calcite concretion, Wisconsin, 7cm high |
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| Septarian concretion, Utah. Septaria are usually solid concretions of impure limestone with polygonal blocks whose cracks have been filled with calcite (two generations, brown and yellow) 10cm across, Utah. They are usually considered as being originally deposited as a gel, which then desiccated and formed shrinkage cracks. |
