Smithsonite after Calcite

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Sharp scalenohedral crystals of what were once calcite measuring to 2.5 cm in height coming off matrix and now replaced by yellowish crystallized smithsonite. In good condition. An excellent hand sized example for this classic Mexican pseudomorph specimen.A pseudomorph is a mineral specimen in which one mineral has replaced another while preserving the original crystals external shape. In the case of smithsonite after calcite, zinc rich solutions chemically replace the original calcite crystal with smithsonite while maintaining the same crystal form. The result is a specimen that looks like a calcite crystal but is actually composed of smithsonite. Such pseudomorphs are valued by collectors because they show the process of mineral replacement while preserving the earlier crystal structure.