Quartz qith sphalerite and chalcopyrite

Exceptional double face specimen of thin and shiny quartz crystals, on a matrix  with 4 large sphalerite(marmatite) crystals covered by shiny chalcopyrite crystals, some of them grought on the sphalerite crystals. On the back side there are small sphalerite and chalcopyrite crystals and 2 flat pseudomorph of quartz after calcite crystals