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Zincite

Discovered in 1845 ; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

(Zn,Mn²⁺)O

Zinc Manganese Oxide

Molecular Weight:

80.34 gm

Composition:

Manganese

6.84 %

Mn

8.83 %

MnO

Zinc

73.25 %

Zn

91.17 %

ZnO

Oxygen

19.91 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Oxides

Strunz 8th Ed. ID:

4/A.03-20

Nickel-Strunz 10th Ed. ID:

4.AB.20

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
A : Metal: Oxygen = 2:1 and 1:1
B : M:O = 1:1 (and up to 1:1.25); with small to medium-sized cations only

Related to:

n/a

Varieties:

None

Synonyms:

Ancramite, Apartalite, Brucite (of Dufrénoy), Red Oxide of Zinc, Red Zink Ore, Ruby Zinc (of Alger), Spartalite, Sterlingite (of Alger)

Crystal Data

Crystallography:

Hexagonal - Dihexagonal Pyramidal

Crystal Habit:

Crystals rare, typically pyramidal, hemimorphic, with large {0001}, to 2.5 cm, rarely curved; in broad cleavages, foliated, granular, compact, massive.

Twinning:

On {0001}, with composition plane {0001}

Physical Properties

Cleavage:

Perfect on {1010}; parting on {0001}, commonly distinct

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

4.0

Density:

5.64 - 5.68 (g/cm³)

Luminescence:

Usually none in medium to darker colored specimens; rarely yellow fluorescence under LW UV from lighter colored specimens. Only light yellow material from Sterling Mine may fluoresce yellow-green under SW UV.

Radioactivity:

Not Radioactive

Optical Properties

Color:

Light to dark Yellow, Yellow-Orange, Orange, deep Red, rarely Green

Transparency:

Transparent, Translucent, Opaque

Luster:

Sub-adamantine to Resinous

Refractive Index:

2.013 - 2.029  Uniaxial ( + )

Birefringence:

0.0160

Dispersion:

0.127

Pleochroism:

None

Anisotropy:

Weak; color in reflected light: light rose brown

Occurances

Geological Setting:

A primary mineral in metamorphosed stratiform zinc orebodies (New Jersey, USA); a secondary mineral altered from other zinc minerals in oxidized zinc-rich ore deposits; a product of volcanism.

Common Associations:

Franklinite, Willemite, Calcite (New Jersey, USA); Zinc, Sphalerite, Smithsonite, Hemimorphite, Hausmannite

Common Impurities:

Mn, Fe

Type Locality:

Franklin Mine, Franklin, Franklin Mining District, Sussex Co., New Jersey, USA; Sterling Mine, Sterling Hill, Ogdensburg, Franklin Mining District, Sussex Co., New Jersey, USA

Year Discovered:

1845

View mineral photos:

Zincite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Zincite is an amazingly beautiful and very rare gem with intense colors of red, orange, yellow and rarely green. Its refractive index is close to a diamond's (2.417) and therefore has lots of fire. Gem quality Zincite crystals have been found in only a few locations in the world. The most notable is the Franklin Mining District, New Jersey. Gems from this location are extremely rare and usually dark red, colored mostly by the iron and manganese content, and associated with Franklinite and Willemite.

Another source of Zincite gems is a smelter at a Zinc mine at Breslau, Silesia, Poland. Zincite crystals were formed accidentally as the result of a chimney fire in a smelter at the Zinc mine. These crystals are not considered synthetic since they weren't grown in a laboratory environment but are not a natural crystal. These crystals have been used to cut some of the brightest and most highly refractive gems with superb colors ranging from deep red to deep green including bright orange, lemon yellow and bright green. Synthetic Zincite gems are also available on the gem market. Synthetic crystals can be colorless, yellow, light green, orange and dark red.

Zincite was originally named "red oxide of zinc" in 1810 by American mineralogist Archibald Bruce (1777-1818) as a chemical name typical of the mineral nomenclature practice of the time. It was renamed "zincite" for its high zinc content in 1845 by Austrian mineralogist Wilhelm Karl von Haidinger (1795-1871). The name Zinc is from the German word Zinke, meaning prong or tooth. American mineral collector Francis Alger (1807-1863) called this mineral "sterlingite" in 1844, while English crystallographer Henry James Brooke (1771-1857) and Welsh mineralogist William Hallowes Miller (1801-1880) named this mineral "spartalite" in 1852.

Distribution: In the USA, from Franklin and Sterling Hill, Ogdensburg, Sussex County, New Jersey; in the Tonopah-Belmont mine, Osborne district, Maricopa County, Arizona, the result of a mine fire; in volcanic ash from Mt. St. Helens, Skamania County, Washington. At Tsumeb, Namibia. From Kipushi, 28 km southwest of Lubumbashi, Katanga Province, Congo (Shaba Province, Zaire). Other localities have been reported but lack supporting data or an accurate location.

Zincite gems for sale: