This is just a fabulous Dalnegorsk galena specimen, for two reasons: one, the spinel-twinning is so wonderfully exaggerated here in these sharp, shiny flat hexagonal crystals. But secondly, it is decorated with sharp sphalerites that are as lustrous as glass. So you have the beautiful sphalerites dominating the left side of the specimen, and the twinned galenas starring on the right.