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  • Density: 19.30 g·cm−3 [in g·cm−3 – water is 1, Pb is 11.3, Os 22.6]
  • Colour: yellow (copper and cesium are the only other coloured metallic elements)
  • Total all-time production worldwide: anticipated to reach 200,000 tonnes in late 2021 [author estimate]
  • Physical properties: most malleable and ductile of metals, unaffected by air, water or most corrosive compounds
  • Dissolves with aqua regia, cyanide and mercury
  • Conversion: 31.01 tonnes equals 1 Moz.

  • Modern uses: jewellery, dental, electronics, computers, bars, coins
  • Monetary use: hard asset to support paper currency
  • Recyling: most of the gold ever mined is still in use
  • Earliest mining: alluvial mining in middle-east and Africa several thousand years ago
  • Price in $US: $250 to over $2000 since 1995. Pegged to US dollar at $35 before 1980s.
  • Price in terms of labour: one ounce of gold has been worth approximately one to two weeks labour [has remained in this bracket for centuries]

  • Minerals with essential gold: gold [Au], maldonite [AuBi], calaverite [AuTe], other tellurides, aurostibite, rhodite, uytenbogaardtite Ag3AuS2, fischesserite (Ag3AuSe2), auricupride, petrovskaite AuAgS
  • Melting point: 1064 °C
  • Boiling point: 2856 °C
  • Naturally-occurring isotope: Au197 only (rest have half lives of less than one year).
  • Atomic weight: 79
  • Atomic mass: 197.0
  • Periodic table column: below Cu and Ag
  • Periodic table row: after Os, Ir, Pt; before Hg, Tl, Pb, Bi
  • Similar elements: include Ag, Cu, PGEs, Bi depending upon chemical environment.
  • Oxidation states: -1, 1, 2, 3, 4, 5. Note +1 and +3 dominate in nature
  • Electronegativity: 2.54 Pauling scale which is very high for a metal cation
  • Electron configuration: [Xe] 4f14 5d10 6s1
  • Ionisation energy: 1st 890.1 kJ.mol-1, 2nd 1980 kJ.mol-1
  • Atomic radius 144 pm
  • Covalent radius 136 +/-6 pm
  • Au1+ 137 pm, very large
  • Au3+ 85 pm
  • Co-ordination chemistry: linear (Au1+), square planar (Au3+)
  • Why is gold yellow?: Gold absorbs blue light to transfer an electron between its 5d and 6s orbitals. The 6s is unexpectedly low energy due to relativistic effects of this heavy element.

  • Gold has two valence states of importance in nature (generally Au3+ in the regolith environment, supergene; and Au1+ in the primary environment, unweathered)
  • Ligands applicable to Au3+ in nature include Cl and S2O3 thiosulfate
  • Ligands of importance for Au1+ in nature include HS bisulfide and Cl
  • Ch.14 errata: Au3+ in the text and figure caption should read Au1+
  • A revised Fig. 14.9 follows omitting the different valence states and only applies for the primary (unweathered) zone. It still highlights the two-fold division of gold-plus and gold-only deposits based upon ligand species.