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ZnCO3 White, yellow, gray, brown, or green secondary carbonate mineral associated with sphalerite and commonly reniform, botryoidal, stalactitic, or granular; hardness is 5 on Mohs scale, and specific gravity is 4.30-4.45; it is an ore of zinc. Also known as calamine; dry-bone ore; szaskaite; zinc spar.



(named after the British chemist and mineralogist J. Smithson, 1765-1829), a mineral of the natural carbonate group; chemical composition, ZnCO3 (ZnO, 64.9 percent; CO2, 35.1 percent). It contains as admixtures Fe, Mn, Cd, Co, Mg, and Pb. Smithsonite crystallizes in the trigonal system. The crystals, which occur rarely, are rhombohedral or scalenohe-dral. Smithsonite usually occurs as granular or earthy masses and stalactitic aggregates with a conchoidal structure. It is, among other colors, white, yellowish, gray, or brown. Its hardness on Mohs scale is 4–4.5, and its density is 4,300–4,400 kg/m3.

Smithsonite is a typical commercial mineral from the zone of oxidation of deposits of primary zinc sulfides in limestones that is formed as a result of the replacement of the limestones. Deposits are found in northern Mexico, Greece (Laurium), Poland (Olkusz), and southwestern Africa (Tsumeb). In the USSR, there are deposits in the Kazakh SSR, Uzbek SSR, and Transbaikalia. [23–1830–]

References in periodicals archive ?
Smithsonite with Hemimorphite The San Antonio Mine Santa Eulalia, Chihuahua, Mexico, 3" tall ex-collection Irv Brown
The rarest color of Namibian smithsonite is a rich cobaltian pink.
The deep green rhombohedral crystals are speckled with white calcites and small crystals of apple-green Smithsonite.
The company offered a group of specimens of Sardinian yellow smithsonite in November 1939, and Prince of Wales Island epidote, blue barite from Sterling, Colorado, red tourmaline crystals from San Jose da Safira in Brazil, and red beryl crystals from Utah in 1940.
Zinc carbonates such as smithsonite and hydrozincite have not yet been identified, and aurichalcite has been found sporadically.
Similar sphaerocobaltite crystals have also come from Aghbar, where they form dark red, rice-grain-like aggregates recalling smithsonite.
At the BrMS symposium in 2001, I had been approached by a member, George Fletcher, who handed me a box containing more than 60 fine micromounts of fluorite, smithsonite, and barite from the mines of Derbyshire.
Copper impurities, for example, can impart a blue or green color to many otherwise colorless species, Thus, that beautiful apple-green smithsonite from Tsumeb which owes its color to the presence of copper was called "herrerite" (named after the local Herero tribe), and the equally attractive Tsumeb adamite colored by the same chromophore was known as "cuproadamite.

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