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Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

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SMITHSONITE


SMITHSONITE (Smithsonit—Smithsonite——митсонит) (Bergmann, 1780), after James Smiths (1765-1829), a British chemist and mineralogist, founder of the Smith. Inst., Wash., who distinguished the mineral from calamine (now hemimorphite).

Composition & Properties. Carbonate – Zn[CO3], trigonal system. Hardness 4.4-5. Density 4.4. Glass luster to pearl one on the cleavage planes. Cleavage in one direction. Fragile. Smithsonite is found in the form of isometric crystals, but more often in spheroid and kidney-shaped aggregates and stripped-colored glassy crusts. Translucent to non-transparent. Color: without admixtures white, colorless; with the admixture of Iron – yellowish, reddish-brown ferrosmithsonite and light brown monheimite; with copper – green and light blue copper smithsonite, bonamite or herrerite; with cobalt – pink to purple cobalt-smithsonite or warrenite; with cadmium – bright yellow turkey-fat ore. Inclusions of native copper form purple zones in sphaerolite and botryoidal aggregates of smithsonite, and inclusions of small crystals of greenockite produce yellow tone.

Deposits. Smithsonite is formed in the oxidation zones of ore deposits. In Russia its best findings are known in the Primorskiy Region – at the Dal’negorskoye deposit; in Transbaikalia – at the Klichka, Zerentui, Taininskiy and Trekhsvyatitel’skiy mines; in Altai – at the Chagirskiy mine, near Zmeinogorsk. In Kazakhstan, in the Rudnyi Altai Mts., smithsonite is found at the Zyryanovskiy mine; in the Balkhash Region – at the Ashchysay deposit, where its ferrous red-brown variety is known under the name of monheimite, which looks like sunstone; in the southwest of Kazakhstan, in the Karatau Mts., smithsonite is found in the form of pink and light bluish-green crystals. In Romania, smithsonite is represented with crusts of different colors, which at the Sasca Montana (Szászkat) deposit have the local name szászkait, or in solid masses, as at the Dognecea deposit,. In Italy, at the Monteponi deposit, Sardinia, they extracted similar yellow ornamental material, which color depended on inclusions of greenockite. In Spain, it is known at the Picos de Europa, Asturias. In Greece, at the Lavrion deposit, they extract bright yellow smithsonite, which is called turkey fat; in Turkey – at the Keban Medan deposit, Elazig vilayet.

However, the best material is extracted in Namibia, at the Tsumeb deposit, in the form of transparent crystals of green, yellow or rose color, up to 10 cm. long, and also in translucent bright green sphaerolites and pseudo stalactites of copper smithsonite up to 7 cm. long. Besides, in Namibia, smithsonite was discovered at the Berg Aukas deposit; and in Zambia – at the Broken Hill deposit, near Kabwe, where it is known in the form of transparent crystals up to 3 cm. In plenty smithsonite is extracted in Vietnam and in China – in the Guangxi-Zhuang autonomus Region. In Australia, at the Broken Hill lead-zinc mine, New South Wales, transparent crystals of yellow smithsonite up to 4 cm. length are called “tear drops”. The admixture of copper in these crystals makes them apple-green in color.

Significant volumes of jewelry-ornamental smithsonite were extracted in the U.S.A., where large sphaerolites of greenish-light blue and apple-green bonamite, in the size of a human’s head, were discovered at the Kelly mine, near Magdalena, New Mexico. Here light blue smithsonite was also found in mixture with white hemimorphiteAztec stone, and green smithsonite with light blue one, so called herrerite. At the same deposit, smithsonite completely replaces fossil shells and stems of lilies. In Arizona, it in good crystals at Bisbee, as sky blue botryoidal aggregates at the Silver Bill mine, Cochise Co. It is also found in Colorado, at the Leadville; in Arkansas – in the form of stripped yellow crusts in the Marion Co.; and other States. In Mexico ornamental material in the form of crusts of smithsonite of different colors is extracted at the Cananea deposit, Sonora; and also at the Choix deposit, Sinaloa; and at the Boleo deposit, Baja California.

Synonyms. Aztekenstein, Germ. | Azulite (azurite), trade name | Zincian rhombohedral baryte | Bonamite, from “bon ami” – a Fr. translation of the surname of owners of the mine, brothers Goodfriend | Calamine, Engl. | Rhombohedral calamine | Chachiguit, Mexican name | Attic emerald, Pliny the Elder | Galmei – general name for yellow and red zinc ores | Calcium galmei | Lead glass | Herrerite, after the Brazilian scientist Herrer | Kieselgalmei | Monheimite, after the Germ. chemist K. Monheim | Zinc ore | Zinc spar | Iron-zinc spar | Szászkait, after the deposit in Hungary | Sacred turquoise | Zincsiderite.

Treatment. As a rough material, smithsonite, available for processing, can reach many kg in mass. To receive brighter color, they cut such material in parallel to the layers of growing. This mineral is used in glyptic, as cabochons, and crystals are faceted for collection purposes. Faceted stones up to 10 ct. display the effect of fire. The most valuable are yellow and rose gems with the effect of fire, a bit cheaper are pure blue or light blue gemstones.

Similarity. Smithsonite looks like turquoise, hemimorphite, jade and chrysoprase.

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