This Leonese mine is near the Riaño reservoir. In this specimen we can see various radial aggregates of acicular prismatic stibnite crystals, with an intense luster and disposed in a calcite matrix that include them. In 1909 Spanish Mining Statistics, indicates the demarcation of 22 properties in this area with the name of "María Teresa" mine (document Nr. 3,260), of antimony, in the name of Policarpo Herrero, domiciled in Oviedo (FMF). A very fine and representative specimen.