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Adamite



This article is about the mineral, for the religious sect see Adamites.
Adamite

Yellow-green adamite in limonite
General
CategoryMineral
Chemical formulaZn2AsO4OH
Identification
ColorYellow, green, rarely white, and occasionally purple
Crystal habitWedge-like prisms typically in druses and radiating clusters - also smooth botryoidal masses.
Crystal systemOrthorhombic; 2/m 2/m 2/m
Cleavageperfect in two directions
Fractureconchoidal
Mohs Scale hardness3.5
Lusteradamantine
Refractive indexnα=1.708 - 1.722, nβ=1.742 - 1.744, nγ=1.763 - 1.773
Streakwhite to pale green
Specific gravity4.4
Other CharacteristicsStrongly fluoresces green in short and long UV light.

Adamite is a zinc arsenate hydroxide mineral, Zn2AsO4OH. It is a mineral that typically occurs in the oxidized or weathered zone above zinc ore occurrences. Adamite is usually yellow in color, but tints of green occur due to inclusion of copper substitutions in the mineral structure. Olivenite is a copper arsenate that is isostructural with adamite and there is considerable substitution between zinc and copper resulting in an intermediate called cuproadamite. Manganese, cobalt, and nickel also substitute in the structure. An analogous zinc phosphate, tarbuttite, is known.

Additional recommended knowledge

The yellow to bright lime-green colored crystals and druze along with its distinctive fluorescence make adamite a favorite among mineral collectors. Found in Mapimi, Mexico; Greece; and California and Utah in the United States.

Adamite was named after the French mineralogist Gilbert Joseph Adam (1795-1881). The type locality is in the Atacama Desert in Chile.  

See also

References

  • Mindat.org
  • Webmineral.com
  • Mineral galleries
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Adamite". A list of authors is available in Wikipedia.
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