Smithsonite
Smithsonite is a zinc carbonate mineral belonging to the calcite group. It is one of the minerals that was once collectively referred to as "calamine," along with hemimorphite. It was given its current name in the mid-19th century in honor of the British mineralogist James Smithson. It is not particularly abundant and is popular for its soft translucent-to-opaque texture and pastel hues.
Smithsonite with charming pastel colors
Basic Information
| English Name | Smithsonite |
|---|---|
| Japanese Name | Ryo-aengyo |
| Chemical Composition | ZnCO₃ |
| Crystal System | Hexagonal (Trigonal) |
| Hardness | 4–4.5 |
| Specific Gravity | Approx. 4.2 |
Colors, Varieties, and Trade Names
A classic source is Ancient Greece, though pure white-to-transparent specimens are actually rare. It exhibits a variety of shades depending on the metal elements present.
- Pink: Colored by Co
- Blue-green: Colored by Cu
- Yellow: Colored by Cd
Bicolor smithsonite, with combinations like blue and pink or pink and yellow, is also known, though the boundaries between colors are often blurred.
Sky-blue smithsonite is sometimes referred to by trade names such as "azurite" or pale blue specimens as "sacred turquoise" (these are distinct from actual azurite and turquoise).
Treatments, Similar Stones, and Other Names
Stones with a porous structure may sometimes undergo impregnation with resin or similar substances.
Similar stones include calcite for colorless varieties, hydrogrossular for pink, and common opal or chalcedony for translucent ones.
Furthermore, along with hemimorphite, it was historically referred to collectively as "calamine." There are many trade names derived from its locality or color, such as "bonamite" (a pale green variety from New Jersey), "herrerite" (blue-to-green from the Salvador region of Mexico), "turkey fat" (yellow colored by Cd), and "Aztec stone" (referring to green smithsonite).
Handling Tips: With a hardness of 4–4.5, it is a relatively soft stone that is prone to scratching. It is better suited for pendants or brooches where there is less risk of impact, rather than rings that are frequently bumped during daily wear. Please also be cautious regarding impregnation treatments and potential confusion with hemimorphite or chalcedony.