Zincite
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Zincite
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Zincite |
|
Chemical composition |
(Zn,Mn)0 Zinc manganese oxide |
|
hexagonal |
Habit |
Pyramidal (hemihedral);
massive |
Cleavage |
Perfect on {10-10}; Parting on {0001} |
Fracture |
conchoidal |
Hardness |
4 |
Optic nature |
Uniaxial + |
Refractive index |
2.013 – 2.029 |
Birefringence |
|
Dispersion |
|
Specific gravity |
5.66 |
Lustre |
Sunadamantine to resinous |
Pleochroism |
|
Fluorescence |
Pale yellow (Extremely
rare!) |
Contents [hide] |
[edit]
Crystal Habit: crystals pyramidal and distinctly hemimorphic; massive
Composition: zinc oxide, ZnO. Usually with minor amounts of manganese (less than
7%), and minor to trace amounts of iron, magnesium and aluminum.
Diagnostics:
Because of its high specific gravity, zincite is unlikely to be confused with any other gem material.
Color: Deep red, deep orange. Manganese is the coloring agent. Green zincite has been observed in nature but to date has not been found in sizes sufficient to facet.
Magnification: black submetallic inclusions of franklinite or hetaerolite (both oxides containing zinc and manganese) are common
Optical and Physical Properties:
Cleavage: perfect on {10-10} ; parting on {000-1}
Fracture: conchoidal
Specific Gravity: 5.66 (measured) 5.67 (calculated)
Hardness: 4
Lustre: subadamantine to resinous
Optical Nature: uniaxial (+)
Refractive Index: ε = 2.013 ω = 2.029
Birefringence:
Dispersion:
Pleochroism:
Spectroscope:
Treatments: none known
Phenomenon: zincite may, in extremely
rarely instances, display a pale yellow fluorescence in long wave ultraviolet
light. This has not yet been documented in cut stones.
Synthetics:
Synthetic zincite flooded the US market in the
late 1980’s and 1990’s,
available in a rainbow of colors from pale green to green, pale red to
deep red, and yellow to deep orange synthetic. This material was derived from
the smokestacks of a metal refinery in
Imitations: none reported
Occurence: the zinc mines of Franklin and Ogdensburg in
Sources:
Anthony, John W., Bideaux, Richard A., Bladh, Kenneth W., and Nichols, Monte C. (1990): Handbook
of Mineralogy: Mineral Data Publishing,
Dunn, Pete J. (1995)
Palache, C. (1935), Minerals of
Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight
Dana and
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