A very ancient specimen showing a quartz matrix with carbonates and pyrite crystals. Covered with thin boulangerite needle-like crystals. Very brilliant and dotted with calcite or dolomite colourless rombohedrons. The original handwritten label of the Astor collection, dated in 1978, indicates it comes from Concepción del Oro, but we believe we can say it is from the Mazapil area, a locality very close to Concepción. In those years, geographical themes were not so determined. Adquired in a very "old mineral shop" in Plaça Reial square, Barcelona.