SMITHSONITE

( Fr- smithsonite; Ger- Smithsonit; Nor- smithsonitt; Rus- )

SMITHSONITE, ZnCO₃

A. Smithsonite (width - 15 cm) from the Kelly Mine, Magdalena, New Mexico; drusylike appearance is due to the growth of a second generation of tiny smithsonite crystals atop the original botryoidal forms. James Duncan collection. (© photo by Jeffrey A. Scovil)

B. Smithsonite (height of paired spheroids - ca. 3.5 cm) from the Kelly Mine, Magdalena, New Mexico. Canadian Museum of Nature. (© photo by Jeffrey A. Scovil)

C. Smithsonite (width - 17.8 cm) from Santa Anita Mine, Choix, Sinaloa, Mexico. George Witters Minerals. (© photo by Jeffrey A. Scovil)

DESCRIPTION: Compact, massive, commonly radiating fibrous smithsonite has sometimes been used as a gemrock.
    Colors - white, grayish white, apple-green, bluish green, pale to sky- to turquoise-blue, purplish, pink, brown, and rarely pink or yellow
    H. 4 - 4½
    S.G. 4.1 - 4.7 (pure - 4.43)
    Light transmission - translucent to subtranslucent
    Luster - silky to pearly to subvitreous
    Breakage - tends to break parallel to the fibers
    Miscellany - effervesces in warm HCl; commonly occurs as botryoidal crusts or masses or as stalactitic-like masses.

OTHER NAMES:

Aztec stone - this term is applied to many things, including greenish smithsonite.
Azulite - misnomer for sky-blue smithsonite.
Bonamite - translucent apple-green smithsonite from Kelly, New Mexico. This name is based on the French words bon ami (=good friend), which, in turn, was based on the English name, Goodfriend Brothers, the New York firm that marketed this material.
Calamine - commonly applied, albeit incorrectly, to smithsonite, especially in England -- see REMARKS, last paragraph.
Turkey fat(or turkey fat ore) - common name, especially among zinc miners, for yellowish, apparently greenockite-pigmented, smithsonite.
Sacred turquoise - misnomer sometimes used in the marketplace for pale blue smithsonite.
Zinc spar - name sometimes given smithsonite, but usually to that which is fairly coarsely crystalline.

USES: Cabochons and freeforms, some of which are attractively multihued, for such things as beads, brooches, pendants, earrings and ornaments.

OCCURRENCE: As a secondary mineral in oxidized zones of zinc deposits.

NOTEWORTHY LOCALITIES: Relatively common in zinc deposits -- e.g., blue, greenish blue and lilac-blue massive material from the Magdalena Mine, near Kelly, Socorro County, New Mexico; yellowish from Marion County, Arkansas; two attractive green cabochons, though apparently rare, from Gila County, Arzizona are shown by Mueller (2012, p.69); several diverse colors including some, in my opinion, especially fine relatively thick pale to sky-blue botryoidal crusts from Sonora and Sinola states, Mexico; blue-green from near Larium, Greece; blue from Cornwall, England, UK; especially several different green hues, and some relatively large crystals as well as more-or-less massive variety, from Tsumeb, Namibia (formerly South-West Africa, earlier German Southwest Africa).

REMARKS: Smithsonite was named after James Smithson (1765-1829), the Englishman who, though he never visited the United States, left his estate with provisos that led, in 1846, to founding of the Smithsonian Institution (U.S. National Museum) in Washington, D.C.

Among the bits of advice Murphy (1962) gives for fashioning smithsonite is the following "Cabochons ... [of smithsonite] should be left rather thick since smithsonite has a pronounced tendency to cleave [sic] parallel with the individual fibers."

According to Gibbs (R. B. 1989. The Magdalena district, Kelly, New Mexico. Minerlogical Record. 20:13-25) "Since the Middle Ages, smithsonite was used in the productdion of brass long before metallic zinc was discovered."

This is one of the mineral materials for which some rather recently contrived metaphysical and healing attributes have been forwarded; and, not remarkably (perhaps?) they have been broken down according to the different colors of the mineral -- e.g., “Green smithsonite is associated with renewal, rebirth and new beginnings. Blue smithsonite fosters emotional, expressiveness. Purple smithsonite awakens psychic abilities. Yellow smithsonite increases energy. Pink smithsonite helps us attract new friends...” (www.tsunyotakohet.com).

Particularly in the past, and especially in England, the name calamine has been applied to smithsonite. This is doubly unfortunate: 1.in most mineralogists' vocabulary calamine referred to Zn₄Si₂O₇(OH)_2·H₂O whereas smithsonite was known to be ZnCO₃ -- two quite different compounds(!) with quite different properties. 2.in 1962, calamine was discredited by the CNMMN of IMA because it was found to a synonym for hemimorphite. Consequently, the term calamine should never have been applied to smithsonite, and since 1962 it should not have been used for any mineral. [But, alas, its use for both persists in some quarters. -- I suspect because both smithsonite and hemimorphite commonly occur together in the oxidized zone of zinc deposits, and some people, particularly nonprofessionals do not know about the conclusions of the IMA commission.] In any case, smithsonite and hemimorphite have properties that make it relatively easy to distinquish between them, even by macroscopic means -- e.g., smithsonite effervesces in warm HCl whereas hemimorphite dissolves in concentrated HCl and hemimorphite is strongly pyroelectric whereas smithsonite is not.

SIMULANTS:

Goodletite??? - O'Donoghue (1997) states that its color resembles the Bonamite variety of smithsonite: However, on the basis of llustrations I have seen (see GOODLETITE entry) I have to wonder if he was looking at something mislabeled goodletite. - [providing criteria seems unnecessary.].

Hemimorphite (calamine) - attractive yellow or blue-green varieties, such as fibrous masses, of this zinc silicate mineral have been fashioned into cabochons and ornaments and sometimes marketed as smithsonite; hemimorphite, by the way, occurs associated with smithsonite in some zinc deposits. - [inferior S.G (~3.4); gelatinizes with acid].

REFERENCES: No general reference.

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