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Smithsonite
Current inventory:  3 gems
 

Chemistry:  ZnCO₃   [Zinc Carbonate]

Discovered in 1832;   IMA status: Valid (pre-IMA; Grandfathered).
Smithsonite is named after James Smithson (1754-1829), British chemist and mineralogist, founder of the Smithsonian Institution (Washington), who distinguished the mineral from Hemimorphite.

Classification

Mineral Classification:

Carbonates

Strunz 8th Ed. ID:

5/B.02-60

5 : Nitrates, Carbonates & Borates
B : Waterfree carbonates without unfamiliar anions
02 : Calcite group

Crystal Data

Crystallography:

Trigonal - Hexagonal Scalenohedral

Crystal Habit:

Uncommon as crystals, to 10 cm, rhombohedral and scalenohedral; additional modifying forms, with curved faces; typically botryoidal, reniform, spherulitic; stalactitic, and as cave pearls; earthy, friable, granular to porous or compact massive.

Twinning:

Rarely

Physical Properties

Cleavage:

[1011] Perfect, [1011] Perfect, 1011 Perfect

Fracture:

Uneven to Conchoidal

Tenacity:

Brittle

Moh's Hardness:

4.0 - 4.5

Density:

4.42- 4.44 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Effervesces in warm acids

Optical Properties

Color:

White, grey, yellow, green to apple-green, blue, pink, purple, bluish grey, and brown

Transparency:

Transparent to Translucent

Luster:

Vitreous to Pearly

Refractive Index:

1.619 - 1.850  Uniaxial ( - )

Birefringence:

0.223 - 0.227  (high)

Dispersion:

0.037  (high)

Pleochroism:

Colorless

Occurances

Geological Setting:

Commonly found as a secondary mineral in the oxidization zone of zinc ore deposits. It can also be found in sedimentary deposits and as a direct oxidization product of sphalerite.

Type Locality:

Mendips at Derbyshire, UK

Year Discovered:

1832

View mineral photos:

Smithsonite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Smithsonite is a rare member of the Calcite mineral group that includes Calcite, Cobaltocalcite, Gaspéite, Magnesite, Rhodochrosite, and Siderite. It is available in several colors that are influenced by the addition of various other minerals. Pink colors are due to the addition of cobalt or manganese, yellows from cadmium, blues and greens from copper. It is also rarely found as colorless. The blue-green Smithsonite from the Kelly Mine in New Mexico, USA has been in high demand for many years. The combination of dispersion almost as high as Diamond and the beautiful, pearly to silky luster and unusual colors makes clean, faceted Smithsonite a magnificent gem. Smithsonite has a high zinc content of about 52%. Smithsonite is available from many localities worldwide.
 

  
Smithsonite gems for sale: