This specimen is majority Galena and contains Quartz (SiO2).

Lustrous gray-metallic Galena crystals with intersecting transparent, colorless Quartz crustals. The Galena crystals are twinning on the {1 1 1} plane following the Spinel Law of isometric twinning resulting in triangular shaped crystals. Sharp, flat faces of the Galena twins with brilliance and mirror luster. Vertically crystallized rosettes cross each at angles. Quartz crystals are transparent, partially covered by Calcite. Krushev dol min, Madan ore field, Rhodope Mountains, Smolyan Oblast, Bulgaria. 7 x 5.5 cm.