Galena – Occurrence, Properties and Distribution

Galena is the primary ore mineral of lead. Its discovery dates back to 3000 BC, and its name is derived from the Latin word galena, meaning dross from melted lead.

Properties of Galena

The key physical properties of Galena are as below:

  • Cell Data
    • Space group: Fm3m
    • a = 5.936
    • Z = 4

  • Crystal Data
    • Cubic
    • Point group: 4/m 3 2/m
    • Crystals: most commonly cubic, crystals to a meter on edge are known; more rarely cubo-octahedral. May be tabular on {001}; also form reticulated masses and skeletal crystals. As cleavable masses coarse to very fine granular; fibrous plumose
      Twinning: twin plane {111}, as both contact and penetration twins; twin plane {114}, lamellar
    • X-ray powder pattern: Synthetic 2.969 (100), 3.429 (84), 2.099 (57), 1.790 (35), 1.327 (17), 1.714 (16), 1.484 (10)

  • Chemical Composition
    Elements Content 1 Content 2 Content 3
    Pb 85.50 85.9 86.60
    Cu 0.07 Trace -
    Sb - 0.7 -
    Bi - 0.2 -
    S 13.31 12.6 13.40

  • Optical Properties
    • Opaque
    • Lustre – Metallic
    • Color- lead-grey, white in polished section

  • Estimated Properties
    Electron density Bulk density (electron density) = 6.23 g/cm3
    note: Specific gravity of Galena = 7.60 g/cm3
    Photoelectric PEGalena = 1623.65 barns/electron
    U = PEGalena x ρelectron density = 10108.40 barns/cm3
    Fermion index Fermion index = 0.19
    Boson index = 0.81
    Radioactivity
     
    GRapi = 0 (Gamma Ray American Petroleum Institute Units)
    Galena is not radioactive

How to Identify Galena

The color of galena is lead-grey, but it appears white in polished sections. It is brittle by nature. Its hardness varies from 2.5 to 2.75. It exhibits a metallic lustre.

Global Distribution

Galena is widely distributed in the following locations:

  • USA – from Coueur d’ Alene district, Idaho; Shoshone Co. Colarado; Mississippi Region; Tri-state District, Missouri
  • Czech Republic – from Pribram
  • Germany – from Saxony, Hesse; Clausthal in Harz Mountains
  • France – from Pontigibaud
  • England – from Alston Moor, Cumbria
  • Scotland – from Wanlockhead, Dumfries
  • Mexico – from Santa Eulalia
  • Ireland – Mogul Mine, Tipperary

Occurrence of Galena and Useful Mineral Association

Galena occurs in a number of environments, such as hydrothermal veins (formed under various temperatures), metamorphic deposits, and in pegmatites. Limestones and dolostones are common in host rocks.

Some of the minerals with which galena is associated are spharelite, marcasite, pyrite, chalcopyrite, siderite, silver minerals, dolomite, quartz, and many other hydrothermal minerals.

References

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