Gold (original) (raw)
Colour:
Rich yellow, paling to whitish-yellow with increasing silver; blue & green in transmitted light (only thinnest folia [gold leaf])
Specific Gravity:
15 - 19.3
Name:
Gold is one of the first minerals used by prehistoric cultures. The Latin name for this mineral was "aurum" and Jöns Jakob Berzelius used Au to represent the element when he established the current system of chemical symbols. The Old English word "gold" first appeared in written form about 725 and may further have been derived from "gehl" or "jehl". May be derived from Anglo-Saxon "gold" = yellow. (Known to alchemists as Sol.)
Copper Group. Gold-Silver Series and Gold-Palladium Series.
A native element and precious metal, gold has long been prized for its beauty, resistance to chemical attack and workability. As it is found as a native element, has a relatively low melting point (1063 degrees Celsius) and is malleable, it has been used by mankind for thousands of years.
Gold is used as a standard for international currency and is also widely used in jewelry, electronics (where its superb properties as a conductor help offset its tremendous cost), dentistry and in photographic processes.
Gold occurs in significant amounts in three main types of deposits: hydrothermal quartz veins and related deposits in metamorphic and igneous rocks; in volcanic-exhalative sulphide deposits; and in consolidated to unconsolidated placer deposits. It may also occur in contact metamorphic or hypothermal deposits (e.g. Skarns), or epithermal deposits such as volcanic fumaroles. It is most commonly found as disseminated grains in quartz veins with pyrite and other sulphides, or as rounded grains, flakes, or nuggets in placer deposits in recent to ancient stream and river deposits. Gold is often panned from such deposits by taking advantage of its high density to wash away the lighter sediments from a pan or sluice.
Nuggets are almost exclusively hypogene in origin, forming mostly in veins, but can be somewhat modified in form and chemistry by weathering, erosion, and transport (Hough et al., 2007).
Long-form identifier:
mindat:1:1:1720:2
d732bdf3-ca18-4058-8314-f9a730a8ad7e
Approved, 'Grandfathered' (first described prior to 1959)
1.AA.05
1 : ELEMENTS (Metals and intermetallic alloys; metalloids and nonmetals; carbides, silicides, nitrides, phosphides)
A : Metals and Intermetallic Alloys
A : Copper-cupalite family
1.1.1.1
1 : NATIVE ELEMENTS AND ALLOYS
1 : Metals, other than the Platinum Group
1.5
1 : Elements and Alloys (including the arsenides, antimonides and bismuthides of Cu, Ag and Au)
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference |
|---|---|---|
| Au | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Au | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Colour:
Rich yellow, paling to whitish-yellow with increasing silver; blue & green in transmitted light (only thinnest folia [gold leaf])
Hardness:
VHN10=30 - 34 kg/mm2 - Vickers
Cleavage:
None Observed
None
Density:
15 - 19.3 g/cm3 (Measured) 19.309 g/cm3 (Calculated)
Comment:
Calculated density at 0° C. Depends on silver content (pure gold is 19.3).
Reflectivity:
| Wavelength | R1 | R2 |
|---|---|---|
| 400nm | 36.8% | 25.8% |
| 420nm | 36.8% | 25.8% |
| 440nm | 36.5% | 25.9% |
| 460nm | 36.1% | 26.0% |
| 470nm | 36.0% | 26.5% |
| 480nm | 36.7% | 27.8% |
| 500nm | 45.3% | 37.9% |
| 520nm | 62.5% | 55.9% |
| 540nm | 74.0% | 69.1% |
| 546nm | 77.0% | 71.5% |
| 560nm | 82.2% | 77.0% |
| 580nm | 86.8% | 82.3% |
| 589nm | 88.2% | 84.1% |
| 600nm | 89.7% | 85.9% |
| 620nm | 91.9% | 88.7% |
| 640nm | 93.3% | 90.3% |
| 650nm | 93.8% | 91.0% |
| 660nm | 94.1% | 91.8% |
| 680nm | 94.8% | 92.5% |
| 700nm | 95.3% | 93.2% |
Graph shows reflectance levels at different wavelengths (in nm). Top of box is 100%. Peak reflectance is 95.3%.
R1 shown in black, R2 shown in red
Colour in reflected light:
Yellow to white with increasing silver, reddish with copper
Internal Reflections:
none
Pleochroism:
Non-pleochroic
Comments:
Reflectivity from Criddle & Stanley (1993)
Common Impurities:
Ag,Cu,Pd,Hg,Bi
Class (H-M):
m_3_m _(_4/_m_32/m ) - Hexoctahedral
Cell Parameters:
a = 4.0786 Å
Unit Cell V:
67.85 ų (Calculated from Unit Cell)
Morphology:
Usually crude to rounded octahedra, cubes, and dodecahedra to 2 cm. Often elongated along [100] or [111] directions, forming herringbone and dendritic twins. Flattened {111} plates with triangular octahedral faces. Rarely as wires ([111] elongation); reticulated; dendritic; arborescent; filiform; spongy; also massive in rounded fragments, flattened grains and scales (gold dust).
Twinning:
Common on (111) to give herringbone twins. Repeated on (111) to give stacks of spinel twins that form hexagonal wires.
Crystal Atlas:
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| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0011140 | Gold | Wyckoff R W G (1963) Second edition. Interscience Publishers, New York, New York Cubic closest packed, ccp, structure Crystal Structures 1 7-83 | 1963 | 0 | 293 | ||
| 0012935 | Gold | Jette E R, Foote F (1935) Precision determination of lattice constants Journal of Chemical Physics 3 605-616 | 1935 | synthetic | 0 | 298 | |
| 0013108 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 293 | |
| 0013109 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 574 | |
| 0013110 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 676 | |
| 0013111 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 777 | |
| 0013112 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 875 | |
| 0013113 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 971 | |
| 0013114 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 1075 | |
| 0013115 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 1179 | |
| 0013116 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 1280 | |
| 0013117 | Gold | Suh I-K, Ohta H, Waseda Y (1988) High-temperature thermal expansion of six metallic elements measured by dilatation method and X-ray diffraction Journal of Materials Science 23 757-760 | 1988 | synthetic | 0 | 1324 | |
| 0014943 | Gold | Owen E A, Yates E L (1933) Precision measurements of crystal parameters Philosophical Magazine 15 472-488 | 1933 | synthetic | 0 | 291 | |
| 0015132 | Gold | Davey W P (1925) Lattice constants of twelve common metals Physical Review 25 753-761 | 1925 | synthetic | 0 | 293 | |
| 0015133 | Gold | Davey W P (1925) Lattice constants of twelve common metals Physical Review 25 753-761 | 1925 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
Geological Setting:
- Primary hydrothermal veins
- Volcanic-exhalative sulphide deposits
- Alluvial and eluvial
Bishnupriya Manipuri:ঔরো
Catalan:Or
Esperanto:Oro
Farsi/Persian:طلا
Gan:金
Haitian:Lò
Irish Gaelic:Ór
Kazakh (Cyrillic Script):Алтын
Korean:금
Kurdish (Latin Script):Zêr
Low Saxon/Low German:Gold
Luxembourgish:Gold
Min Nan:Au
Mongolian:Алт
Norman:Or
Norwegian (Nynorsk):Gull
Scottish Gaelic:Òr
Simplified Chinese:自然金
Tajik (Cyrillic Script):Зар
Uzbek (Latin Script):Oltin
Other Members of this group:
| Copper | Cu | Iso. m_3_m _(_4/_m_32/m ) : F m_3_m |
|---|---|---|
| Maldonite | Au2Bi | Iso. m_3_m _(_4/_m_32/m ) : F d_3_m |
| Silver | Ag | Iso. m_3_m _(_4/_m_32/m ) : F m_3_m |
Associated Minerals Based on Photo Data:
Thermal Behaviour:
Melting Point: 1062.4° ± 0.8°
Notes:
Completely soluble with copper. Insoluble in acids except for aqua regia, with incomplete separation if more than 20% of silver is present.
Reported as spongy alteration pseudomorphs after calaverite (Cripple Creek).
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Electrical conductor, transparent reflective coating, jewelry, dentistry, coinage, decorative coatings
An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.
Reference List:
Chumakova, Aleksandra, Kirner, Felizitas, Chumakov, Andrei, Roth, Stephan V., Bosak, Alexeï, Sturm, Elena V. (2023) Exploring the Crystalline Structure of Gold Mesocrystals Using X-ray Diffraction. Crystals, 13 (8) doi:10.3390/cryst13081204
Showing 39 significant localities out of 36,789 recorded on mindat.org.
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