This is an electric, neon green smithsonite variety often referred to as "sugar smithsonite" for its sparkly appearance. It is a solid plate composed of small smithsonite crystals, all grown together, that appears to have grown as a cast over another mineral species that is now removed. Such pieces are obviously more delicate and fragile than normal matrix-bound smithsonite, and the survival rate was simply smaller as a result. This beautiful piece is complete and 3-dimensional. It is translucent to light. This probably would have been mined in the 1970s or early 1980s. Joe Budd photos.