Smithsonite belongs to the calcite group, a group of related carbonates that are isomorphous with one another. Smithsonite has a silky to pearly luster. This luster along with it's botryoidal structure gives Smithsonite an interesting play of light. Almost as if it were lit from beneath. It is essentially zinc carbonate, but the zinc is usually partially replaced with other elements. These elements are responsible for the great color variations that this mineral exhibits. This Aqua color is distinctive of the New Mexico Kelly Mine.