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[Cesar M. Salvan]

In 1959, the famous Spanish collector Joaquin Folch i Girona collected some samples containing beautiful groups of yellow-orange sub-milimetric crystals in the “Esperanza” uranium mine, in Villar de la Yegüa (Salamanca, Spain). Mr. Folch kept the samples in his collection, together with other sample of the same species, a present from Prof. Antonio Arribas, under the denomination “renardite”.

In those days, renardite was an accepted denomination for a lead and uranyl phosphate belonging to the phosphouranylite group. However, in those days the actual nature of renardite and dewindtite as separate species was discussed and, at present, both species are recognized as undistinguishable and the renardite denomination is considered an obsolete name for dewindtite.

Now, the historical uranyl specimens of the Folch collection are under study in order to establish the actual species present, in the framework of a revision of the uranium mineralogy on Iberian peninsula. After the revision of the Folch´s “renardite” specimens, we found an interesting association of dewindtite, kasolite and phosphohedyphane, the last described for the first time in a Spanish deposit.
In the samples of “Esperanza” mine, the phosphohedyphane is identifiable as very small greenish, white or colorless hexagonal prisms forming parallel or sub-parallel growths that constitute the base for the dewindtite groups. A second generation of phosphohedyphane is observable after the uranyl minerals, forming minute crystals visible only under scanning electron microscope.

Our results remark the scientific potential of a well conserved and documented private collection. Thanks to the efforts of Joaquin Folch, a completely “restored” mine site still give us surprises!

note: The study of the Folch specimens is possible thanks to the collaboration of Jordi Fabre and the Natural Sciences Museum of Alava (Spain).