At the beginning of 2014, reviewing some specimens from the Santa Matilde open pit we found into the vugs some groups of lanceolated, fibrous or equidimensional crystals, with pink, beige to white colours, those aroused our interest. After some analysis we could identify as fluorcalcioroméite species (Ca,Na)₂Sb⁵⁺₂O₆F,OH), with a small percentage of oxyplumboroméite (Pb₂Sb₂O₇, due to the presence of lead). Both species belong to the isometric system. But the observed symmetry indicated that they are, highly probable, a pseudomorph after stibnite crystals. This is the first report of this mineral in the Iberian Peninsula. Nowadays this quarry is completelly filled by rubble.
In this specimen we can see some several aggregates in the cavity formed by lanceolated to fibrous crystals, with luster, beige tone, accompanied by aesthetic baryte crystals. We will send a copy of the analysis (SEM-EDS, XRD) to the buyer.