carbonates
Smithsonite
Zn(CO3)
- Also known as
- calaminezinc sparturkey fat ore
- Crystal system
- trigonal
- Hardness
- 4–4.5 on the Mohs scale
- Lustre
- vitreous
- Colour
- Blue-green most famously, also pink, yellow, white
- Where it forms
- In the oxidised zone above zinc deposits, usually as botryoidal crusts rather than crystals.
- Chiefly from
- Kelly Mine, New Mexico, United StatesTsumeb, NamibiaSardinia, ItalyGreece
Why it is that colour
Copper gives the blue-green, cobalt the pink, cadmium the yellow. Pure smithsonite is white.
Safety
Zinc carbonate is comparatively benign — calamine lotion is named after this mineral. It is soft and dissolves in acid. Safe to handle; do not powder or put in water.
Where it comes from
A zinc ore of historic rather than current importance. The Kelly Mine in New Mexico produced the classic blue-green material.
Historical use
Named after James Smithson, the English chemist whose bequest founded the Smithsonian Institution — he distinguished zinc carbonate from zinc silicate in 1802, and the mineral was named for him after his death. Calamine, the traditional zinc ore used to make brass, was this mineral, and calamine lotion inherits the name.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
Worth knowing
James Smithson is an odd figure to find in a mineral collection. He was an English chemist, the illegitimate son of a duke, who never visited America and left his entire fortune to the United States to found an institution for the increase and diffusion of knowledge. Congress argued about whether to accept it for a decade. The Smithsonian exists because of that bequest, and this mineral is named after him.
Brass was made for centuries before anyone knew zinc was an element, by heating copper with calamine — this mineral — and charcoal. The zinc was reduced and absorbed directly into the copper without ever appearing as a metal, which is why brass predates the isolation of zinc by a very long way.
Identity checked against IMA-CNMNC master list, June 2025.