EF36AM6: Very sharp crystals of Sphalerite (variety marmatite), with the dominant forms of a tetrahedron beveled by minor crystal forms, extraordinarily lustrous, on matrix, with water-clear Quartz crystals. A very aesthetic specimen, from a classic locality.
Madan mining area, Rhodope Mountains, Smolyan Oblast  Bulgaria

Specimen size: 20.8 × 15.2 × 4.4 cm = 8.19” × 5.98” × 1.73”

Main crystal size: 2 × 1.6 cm = 0.79” × 0.63”