“Reference: TT13AN2 Group of Siderite crystals with sharp crystal forms, with slight curvatures, a satin luster and a highly contrasted double coloration, with darker and lighter brown areas. On matrix, with small crystals of Calcite and Sphalerite. We will send the specimen in its original Perky box from the Robert J. Noble collection, which also contains the label, which shows that it was previously in the Alfredo Petrov collection. Siglo Veinte Mine, Llallagua, Rafael Bustillo Province, Potosí Department  Bolivia Specimen size: 2.6 × 2.5 × 1.7 cm = 1.02” × 0.98” × 0.67” Main crystal size: 2 × 1.4 cm = 0.79” × 0.55””