- 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.
