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Download hereGENERAL DESCRIPTION
Galena is a lead sulphide. It is the principal lead ore whose exploitation started during the Antiquity. It was also used as black dyeing in old Egypt.
In 1874, Karl Ferdinand Braun discovered its semiconductor properties. This discovery will lead this researcher to carry out, in 1906, the first radio set, known as the "galena radio". A Nobel Prize was given to him for this discovery.
Galena often crystallizes as cubes but also octahedras. Its crystals are of a characteristic metal gray color. Its relatively high density is another character which makes easy its identification.
Silver (Ag) can partially replace lead (Pb) in galena but silver is mostly present as native silver in galena. When the content reaches silver 1%, galena is also mined as a silver ore. Fairly abundant, galena can be found in various geological contexts: hydrothermal veins, sedimentary rocks...
The German deposits of Freiberg (Saxony) and Clausthal (Harz) fed the crystal collections with samples showing crystals of galena with beautiful facets. The mines of the district of Alston Moor in (United Kingdom) and of the district Viburnum Trend (USA) provided superb crystals. Many other deposits in Peru, Macedonia, Romania, Russia also produced exceptional galenas.
In France, the deposits of Pontgibaud (Puy-de-Dôme), Pontpéan (Ile and Vilaine) and Sainte-Marie aux Mines (Bas-Rhin) provided many remarkable samples to the collectors.
The type of this species and its place of conservation are not definable because this species is well known since Antiquity.
HISTORY : Name inspired from the Greek word "γαλένε" [galêne] meaning "lead" and from Latin "galena" meaning "lead mineral"
Species described by Cauis Plinius Secundus better known as Pliny the Elder (23-79 après J.C.), an ancient author, naturalist or natural philosopher and naval and military commander
Type-locality : unknown
ANCIENT NAME : Mine de plomb grise, plomb sulfuré
CHEMICAL FORMULA : Pb S
CRYSTAL SYSTEM : Cubic
COLOR : Lead gray
DIAPHANIETY : Opaque
LUSTER : Metallic
STREAK : Gray
MORPHOLOGIE : Cubic crystals, seldomly cubo-octahedra or octahedra crystals
HARDNESS : 2,5-2,75
CHEMICAL CLASS: 7,57
DENSITY : II - Sulfides, arsenides, antimonides and selenides
GROUP : Galena
STRUNZ CLASS BEFORE 2001 : 2/C.15-40
STRUNZ CLASS AFTER 2001 : 2.CD.10
