Adelite

The rare mineral adelite, is a calcium, magnesium, arsenate with chemical formula CaMgAsO4OH. It forms a solid solution series with the vanadium-bearing mineral gottlobite. Various transition metals substitute for magnesium and lead replaces calcium leading to a variety of similar minerals in the adelite - duftite group.

Adelite
Pinkish crystal aggregates of adelite from the Franklin deposit in Ogdensburg, New Jersey
General
CategoryAdelite-descloizite group
Formula
(repeating unit)
CaMg(AsO4)(OH)
Strunz classification8.BH.35
Dana classification41.5.1.1
Crystal systemOrthorhombic
Crystal class2 2 2 - Disphenoidal
Space groupP212121
Identification
ColorColourless, white, grey, bluish grey, yellowish grey, yellow, pale green, pinkish brown, brown
Crystal habitElongate crystals, massive
CleavageNone Observed
Mohs scale hardness5
LusterVitreous, Greasy
DiaphaneityTransparent, Translucent
Specific gravity3.73 to 3.79
Optical propertiesBiaxial (+), colorless (transmitted light)
References[1]

Adelite forms variably colored (blue, green, yellow and grey) crystals in the orthorhombic crystal system. The form is typically massive. It has a Mohs hardness rating of 5 and a specific gravity of 3.73 to 3.79.

It was first described in 1891 from Värmland, Sweden. Its name comes from the Greek word for indistinct.

Geologic occurrence

Adelite has been found in ore deposits in Algeria, Germany, Italy, Sweden and the USA.[1]

See also

References

Bibliography

  • Palache, P.; Berman H.; Frondel, C. (1960). "Dana's System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. (Seventh Edition)" John Wiley and Sons, Inc., New York, pp. 804-806.


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