1219 Calcite, after Aragonite, Fort Collins area, Larimer Co., Colorado, USA

Pseudomorph. Labelled as calcite ps hanksite, Larimer Co., California. Described as rarely seen pseudomorph with label indication that it was in the American Museum Natural History and dated 12/11/78. Diameter is 2.5 cm. There are two issues with this. Firstly, it is calcite after aragonite. Secondly, Larimer Co. is in Colorado. Aragonite is recorded from there (Occurs near Fort Collins in clay, Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana). I can see that it would have been easy to misread Col for Cal. Clifford Frondel in Catalogue of Mineral Pseudomorphs in the American Museum (1935) says These are sometimes erroneously made pseudomorphs after hanksite. Acquired by Jake Slagle from Jasun McAvoy (Mineralman), who said that it was (or probably was) from a flat of thumbnails previously in Larry Conklin’s basement, which Larry obtained from AMNH in a trade.

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