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Zincite from Arizona.jpg
Crystal blades of zincite
Category Oxide mineral
(repeating unit)
Strunz classification 4.AB.20
Dana classification
Crystal system Hexagonal
Crystal class Dihexagonal pyramidal (6mm)
H-M symbol: (6mm)
Space group P63mc
Color Yellow-orange to deep red, rarely yellow, green, colorless
Crystal habit Disseminated – occurs in small, distinct particles dispersed in matrix.
Twinning On {0001}
Cleavage On {1010}, perfect; parting on {0001}
Fracture Conchoidal
Tenacity Brittle
Mohs scale hardness 4
Luster Subadamantine to resinous
Streak Yellowish orange
Diaphaneity Translucent, transparent in thin fragments
Specific gravity 5.64–5.68
Optical properties Uniaxial (+)
Refractive index nω = 2.013, nε = 2.029
Birefringence δ = 0.016
References [1][2]

Zincite is the mineral form of zinc oxide (ZnO). Its crystal form is rare in nature; a notable exception to this is at the Franklin and Sterling Hill Mines in New Jersey, an area also famed for its many fluorescent minerals. It has a hexagonal crystal structure and a color that depends on the presence of impurities. The zincite found at the Franklin Furnace is red-colored, mostly due to iron and manganese dopants, and associated with willemite and franklinite.

Zincite crystals can be grown artificially, and synthetic zincite crystals are available as a by-product of zinc smelting. Synthetic crystals can be colorless or can range in color from dark red, orange, or yellow to light green.

Synthetic zincite crystals

Both natural and synthetic zincite crystals are significant for their early use as semiconductor crystal detectors in the early development of crystal radios before the advent of vacuum tubes. As an early radio detector it was used in conjunction with another mineral, galena, and this device was known as the cat's-whisker detector.

See also[edit]


  1. ^ Zincite. Handbook of Mineralogy
  2. ^ Zincite. Mindat

External links[edit]