Adelite – Occurrence, Properties, and Distribution

Topics Covered

Introduction to Adelite
Properties of Adelite
How to Identify Adelite
Global Distribution
Occurrence of Adelite and Useful Mineral Association
References

Introduction to Adelite

Chemical Formula – CaMg (AsO4)(OH)

Adelite was named after the Greek word for indistinct, due to the fact that the mineral lacks transparency.

Properties of Adelite

The following are the key properties of Adelite:

  • Cell Data
    • Space group: P212121
    • a = 7.43
    • b = 8.85
    • c = 5.88
    • Z = 4

 

  • Crystal Data
    • Orthorhombic
    • Point group: 222
    • Tabular on {001}, or elongated along [100], showing {100}, {001}, {110}, {011}, {221}, to 5mm
    • May be hemispherulitic
    • Commonly granular, massive
    • X-ray powder pattern: 3.16 (10), 4.13 (7), 2.59 (7), 2.33 (7), 1.609 (7), 4.96 (6), 2.98 (6)

 

  • Chemical Composition
    Elements Content 1 Content 2
    As2O5 50.28 52.17
    CaO 24.04 25.45
    MgO 17.90 18.30
    H2O 3.90 4.08
    PbO 2.79 -
    MnO 0.48 -
    CuO 0.32 -
    BaO 0.23 -
    FeO 0.08 -
    Cl Trace -
    Total 100.02 100.00

 

  • Optical Properties
    • Translucent to transparent
    • Optical class: Biaxial (+)
    • Orientation: X = a; Y = c; Z = b
    • Dispersion: r < v , weak
    • α = 1.712; β = 1.721; γ = 1.731
    • 2V(meas.) = 68° to ~90°

 

  • Estimated Properties
    Electron density Bulk density (electron density) = 3.62 g/cm3
    note: Specific gravity of Adelite = 3.76 g/cm3.
    Photoelectric PEAdelite = 25.46 barns/electron
    U = PEAdelite x ρ electron density = 92.10 barns/cm3
    Fermion index Fermion index = 0.01
    Boson index = 0.99
    Radioactivity
    Adelite is not radioactive

How to Identify Adelite

Adelite can be identified in the field by its color variations, such as blue-gray, green, gray, yellow, and light green. It is transparent, with indistinct cleavage. This mineral has a resinous luster, with a white streak. The fracture on this mineral is conchoidal. It has a non-fluorescent luminescence.

The density of Adelite is 3.73 to 3.79 g/cm3, with a hardness of 5 – approximate to apatite.

Global Distribution

Adelite is distributed in the following places:

  • Sweden - From Langban and at Jakobsberg, Varmland, and in the Kittel mine, Nordmark
  • Germany - At St. Andreasberg, Harz Mountains
  • USA - From Sterling Hill, Ogdensburg, and Franklin, Sussex Co. New Jersey

Occurrence of Adelite and Useful Mineral Association

Adelite occurs in a rare mineral in a metamorphosed Fe–Mn orebody; and on willemite-franklinite ore from a metamorphosed stratiform zinc orebody.

It is often associated with minerals such as arsenoclasite, sarkinite, braunite, fredrikssonite, hedyphane, hausmannite, magnetite, copper, hodgkinsonite, barite, rhodochrosite, allactite, franklinite, willemite, alleghanyite, kraisslite, sphalerite, chlorophoenicite, rhodochrosite, willemite, franklinite; johnbaumite–svabite, zincite, barite, and calcite.

References

 

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