What is the molecular formula of galena



Galena (galena)
Galena (galena); Site: Slovakia, Banská Štiavnica
Chemism PbS
Mineral grade Sulfides, sulfosalts
II / C.15-40 (after Strunz)
2.8.1.1 (according to Dana)
Crystal systemcubic
Crystal class isometric-hexoctahedral
colour lead gray
Line color lead gray
Mohs hardness 2,5
Density (g / cm³) 7.4 to 7.6 g / cm3
shine Metallic luster
transparency opaque
fracture shell-like
Cleavage completely after {100}
Habitus Cubes, octahedra, often combined, tabular, skeletal crystals and aggregates
Frequent crystal faces {100}, {111}, {110}
Twinning {111}
Crystal optics
Refractive index 3.90 (at 590 nm)
Birefringence
(optical orientation)
Pleochroism
Angle / dispersion
of the optical axes
2vz ~
Other properties
Phase transitions
Melting point
Chemical behavior dissolves in ENT3
Similar minerals
radioactivity not radioactive
magnetism not magnetic
Special marks

Galena or Galena, also known under the chemical name lead (II) sulfide, is a widespread mineral from the mineral class of sulfides with the molar ratio metal: sulfur = 1: 1. It crystallizes in the cubic crystal system with the chemical formula PbS and can contain up to one Percent silver included.

Galena often develops perfectly cube-shaped crystals, but also octahedral, more rarely tabular or skeletal crystals and massive aggregates of a lead-gray color and line color. It has a hardness of 2.5 and 7.4 to 7.6 g / cm3 a comparatively high density. Galena shows a metallic sheen.

Etymology and history

Galena can be considered one of the first minerals to be mined by humans: the Babylonians smelted it and the Romans also coveted it. Its name “Galena” lives on today in the scientific name “Galenite”.

Varieties and modifications

The only known variety so far is that Stone mannite.

Education and Locations

Galena is formed in metamorphic rock as well as in volcanic sulphide deposits, there mostly associated with copper ores. It also occurs in ore deposits in reef limestone and dolomite rock.

Locations include Bad Bleiberg in Carinthia; in Germany Freiberg / Saxony in the Ore Mountains; hydrothermal ore veins near Clausthal-Zellerfeld, Bad Grund and St. Andreasberg in Ober- and Neudorf in the eastern Harz; the synsedimentary-exhalative-submarine ore deposit in Rammelsberg near Goslar; in Triassic sediments near Mechernich, Maubach in North Rhine-Westphalia and Wiesloch south of Heidelberg, Walhausen in Saarland.

use

Because of its lead content of 87 percent, galena is the most important ore for the extraction of lead and because of its silver content of up to approx. 1% it is also the most important silver ore.

Already in the Old Kingdom of Egypt it was used for make-up (as white lead, but also to emphasize the eyes).

In early radio technology, galena was used as a rectifier (demodulator) in detector receivers.

See also

literature

  • Martin Okrusch, Siegfried Matthes: mineralogy. 7th edition. Springer Verlag, Berlin 2005, ISBN 3-540-23812-3
  • Stefan White: The great lapis mineral directory. 4th edition. Christian Weise Publishing House, Munich 2002, ISBN 3-921656-17-6
  • Edition Dörfler: Minerals encyclopedia, Nebel Verlag, ISBN 3-89555-076-0

Categories: Mineral | Lead mineral | Cubic crystal system | Sulphides and sulphosalts | Sulfur mineral