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A Geoscience Digital Image Library

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TitleAragonite “toadstool concretions” from Slope County, North Dakota
DescriptionAragonite (CaCO3) has many different habits. These mushroom-like aragonite nodules come from a bentonite in the lower Brule Formation (Oligocene). They are about 3 cm across. Aragonite is a polymorph (has the same composition but different atomic arrangement and crystal forms) of calcite, which is more common.
LocationUSA ▹ North Dakota ▹ Slope County. Near Amidon. Chalky Buttes, SW 1/4 sec 30, T. 134 N, R 100 W.
PhotographerNessa Eull. 2001-06-13.
CollectionUniversity of North Dakota Mineralogy Collection #687.
Key wordsaragonite, North Dakota
Tech details356 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens.
GeoDIL number729