About
Smithsonite rarely occurs in visible crystals. The only two locations to produce large crystals of significance are Tsumeb, Namibia; and the Kabwe Mine (Broken Hill), Zambia. Virtually all other findings of this mineral are in globular or botryoidal-like forms. Many of the rounded forms have a very distinct feathery or sparkling light effect. Botryoidal Smithsonite aggregates are sometimes lubricated with oils by dealers to enhance luster and appeal to collectors.
Smithsonite belongs to the calcite group of minerals, a group of related carbonates that are isomorphous with one another. They are similar in many physical properties, and may partially or fully replace one another, forming a solid solution series. All members of the calcite group crystallize in the trigonal system, have perfect rhombohedral cleavage, and exhibit strong double refraction in transparent rhombohedrons.
Smithsonite is named in honor of James Smithson, the founder of the Smithsonian Institution.
Crystal Forms & Aggregates
Smithsonite is also known to form pseudomorphs of other minerals such as Calcite, Galena, and Fluorite, assuming the crystal shapes of those minerals.
Other ID Marks
2) Clear, transparent, rhombohedral crystals exhibit strong double refraction.
Complex Tests
Striking Features
Environment
Varieties
✓ common · ✗ uncommon
- Bonamite— Blue or green globular Smithsonite with a pearly luster. This term is usually used to describe Smithsonite in the gem trade.
- Cadmium Smithsonite— Yellow or yellow-green Smithsonite colored by cadmium impurities.
- Copper Smithsonite— Blue to green Smithsonite colored by copper impurities.
- Dry Bone Ore— Describes the massive, porous, and dull variety of Smithsonite, which often assumes a honeycomb shape.
- Turkey Fat Ore— Describes globular, botryoidal, and stalactitic forms of yellow Smithsonite.
Uses
Noteworthy Localities
Individual Smithsonite crystals and crystal clusters of all colors are well-known from Tsumeb, Namibia. Two other African localities which provided visible crystals of this mineral are Berg Aukas, Grootfontein, Namibia; and the Kabwe Mine (Broken Hill), Zambia. The famous Australian locality of Broken Hill, New South Wales, is known for its abundance of minerals including Smithsonite.
Mexico has two outstanding Smithsonite localities which contain beautifully colored Smithsonite, including deep pink and electric green colors. These are the Refugio Mine, Choix, Sinaloa; and the San Antonio Mine, Santa Eulalia District, Chihuahua.
The U.S. has many fine Smithsonite occurrences; perhaps the most famous being the Kelly Mine, Magdalena, Socorro Co., New Mexico. The No. 79 Mine, Hayden, Gila Co., Arizona is known for its dark and apple-green Smithsonite. Bright yellow and orange-yellow specimens have come from Rush, near Yellville, Marion Co., Arkansas. A large industrial zinc deposit produced Smithsonite in Leadville, Lake Co., Colorado. Other localities are Cerro Gordo, Inyo Co., California; the Hidden Treasure Mine, Ophir Hill, Tooele Co., Utah; and Mineral Point, Iowa Co., Wisconsin.
Common Mineral Associations
Distinguishing Similar Minerals
Prehnite - Harder (6 - 6½), doesn't effervesce in hydrochloric acid.
Wavellite - Softer (3½ - 4), lighter in weight, doesn't effervesce at al
Calcite - Softer (3), strongly effervesces in hydrochloric acid, even if acid is cold and diluted.
Chrysocolla - Softer, usually has a deeper color. Otherwise difficult to distinguish.
Photos
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