Smithsonite

Smithsonite from the El Refugio Mine, Choix Municipality, Sinaloa, Mexico, measuring 69 × 43 × 22 mm and weighing 107 grams. A second Smithsonite in this sale, from a quite different part of the world to the Greek piece above.

Smithsonite, zinc carbonate, ZnCO3, forms wherever Sphalerite is weathered in the oxidised zone of a zinc deposit, and Sinaloa's base-metal mining districts, hosted in skarn and vein systems related to the region's igneous intrusions, have produced it in a range of habits and colours depending on the trace elements available locally. Mexico as a whole is one of the world's most productive countries for secondary zinc, lead and silver minerals, and Sinaloa's deposits are part of that wider picture.

Comparing this piece against the Greek Smithsonite in the same sale is a good way to see how differently the same species can present depending on its locality's particular chemistry and conditions. This piece is from the David Vince Collection.