| Mineral class: | Carbonate |
| Composition: | Zinc carbonate, ZnCO3 |
| Hardness: | 5 |
| Color: | Brown; sometimes green, blue, pink, or white |
| Cleavage: | Rarely seen |
| Crystal form: | Rhomb-shaped crystals rare. Usually massive, honeycomb, or nodular appearance. |
| Environment: | Forms from reaction of carbonated water with sphalerite. |
| Uses: | Zinc ore |
| Comments: | Scratched by knife but not by penny. Fizzes in HCl. Named in honor of the patron of the Smithsonian Institution, the Englishman James Smithson. |