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Download hereGENERAL DESCRIPTION
Native gold consists of nearly pure gold. It is, at the same time, a mineral and a very prospected metal. Of bright metallic yellow colour, it can be associated to other metals and constitute natural alloys. One keep the name “native gold” until the gold content is higher than 75 wt.%. It is formed in various contexts: hydrothermalism, volcanism but is also found in the alluvia resulting from the destruction of the hydrothermal and volcanic deposits. Gold can be associated to quartz, pyrite, chalcopyrite...
It one of the first metals discovered and is used by humanity. He is presented in the form of rolled nuggets, of spangles, metallic plates and much more rarely as octahedral crystals.
It is often disseminated inside the rocks (volcanic, sedimentary) in small quantities. To find such a heavy mineral in sediments, gold is separated from sediments thanks to the use of a gold pan.
The gold bearing localities are very numerous, but little produced remarkable samples. Among most known: the mine Eagle's Nest, Placer Co, California; Beresovk in Russia; Kalgoorlie in Australia; Verespatak in Romania, or the gold district of the Transvaal in South Africa; without forgetting the important deposits known in Canada, China and the remarkable crystals produced in Venezuela.
In France, it is present in many rivers (alluvial) as spangles. It is frequently found in the Massif Central in many arsenic mines, exploited since the Romans, in La Gardette in Isère (French Alps) where it is associated quartz; the La Lucette antimony mine in Mayenne, of Rouez (Sarthe) or Salsigne (Aude). These last two mines are the top two richest gold mines of Europe. In French Guyana, its intensive mining leads to the destruction of the primary forests despite of law enforcements.
Being malleable, it is possible to work it to manufacture objects and jewels. It also served as a reference for currencies, it is nowadays lesser used for the ingots and some currencies. It is an excellent thermal and electric driver, one uses it to manufacture chips and some electronic components.
The type of this species and its place of conservation are not definable because this species is well known since Antiquity.
HISTORY : Name derived from the Latin "aurum" who will give its chemical symbol (Au)
Species known since the Antiquity
Type-locality : unknown
CHEMICAL FORMULA : Au
CRYSTAL SYSTEM : Cubic
COLOR : Golden yellow, reddish yellow to silvery yellow
DIAPHANIETY : Opaque
LUSTER : Metallic
STREAK : Bright yellow
MORPHOLOGIE : Octahedral crystals, dodecahedra, cubic. Dentritic, massive. As nuggets, en spangles
HARDNESS : 2,5-3,0
CHEMICAL CLASS: 19,302
DENSITY : I - Elements
GROUP : Copper
STRUNZ CLASS BEFORE 2001 : 1/A.01-40
STRUNZ CLASS AFTER 2001 : 1.AA.05
