GoldAu
c 2001-2005 Mineral Data Publishing, version 1

Crystal Data: Cubic. Point Group: 4/m 3 2/m. As octahedra, dodecahedra, and cubes,
typically crude or rounded, to about 5 cm; also elongated k [111]. In twinned and parallel crystal
groups; reticulated, dendritic, arborescent, platy, filiform, spongy; massive, and in roundednuggets; scales and flakes. Twinning: Common on {111}; repeated to form reticulated anddendritic aggregates.
Physical Properties: Fracture: Hackly. Tenacity: Very malleable and ductile.
Hardness = 2.5–3 VHN = 30–34, 44-58 (argentian) (10 g load). D(meas.) = 19.3
D(calc.) = 19.302
Optical Properties: Opaque in all but thinnest foils. Color: Gold-yellow with a reddish
tint when pure, silver-white to copper-red when impure; blue and green in transmitted light.
Luster: Metallic.
R: (400) 36.8, (420) 36.8, (440) 36.4, (460) 36.1, (480) 36.7, (500) 45.3, (520) 62.5, (540) 75.0,(560) 82.2, (580) 86.8, (600) 89.7, (620) 91.9, (640) 93.3, (660) 94.1, (680) 94.8, (700) 95.3Cell Data:

Space Group: F m3m. a = 4.0786

Z=4X-ray Powder Pattern: Synthetic.
2.355 (100), 2.039 (52), 1.230 (36), 1.442 (32), 0.9357 (23), 0.8325 (23), 0.9120 (22)Chemistry:
Au
Cu

(1)
99.6
0.1

Ag

(1)
0.1

Total 99.8
(1) Porthcurnick Beach, Cornwall, England; by electron microprobe. Commonly contains Ag, Cu,Fe; rarely Pb, Ti, Sb, Hg, V, Bi, Mn, As, Sn, Zn, Pd, Pt, Cd, many other elements.
Polymorphism & Series:Forms a series with silver.

Occurrence: Widespread in very small quantities in rocks of many kinds throughout the world,and in sea water. In veins of epithermal origin, typically in quartz with pyrite and other sulfides,
and with tellurides; in pegmatites; in contact metamorphic deposits. Common in placers.
Association: Pyrite, chalcopyrite, arsenopyrite, pyrrhotite, sylvanite, krennerite, calaverite,altaite, tetradymite, scheelite, ankerite, tourmaline, quartz.
Distribution: Many localities for fine specimens. In Russia, in Siberia, along the eastern slopeof the Ural Mountains; important localities near Yekaterinburg (Sverdlovsk), as at Beresovsk; inthe Miass district; large crystal groups from along the Lena River, Sakha. Sharply crystallizedfrom Romania, at Roşia Montană (Verespatak) and Săcărı̂mb (Nagyág). In Australia, manyoccurrences, as at Bendigo, Ballarat, and Matlock, Victoria; along the Palmer River and atGympie, Queensland; from Kalgoorlie, Western Australia, with gold telluride ores, also verylarge alluvial nuggets. At the Porgera mine, Mt. Kare, Papua New Guinea. The world’s mostimportant gold district is the Witwatersrand, Transvaal, South Africa, which, however, only rarelyproduces crystalline material. In Canada, especially in Ontario, in the Porcupine and Hemlodistricts. In the USA, in California, in the Mother Lode belt of the Sierra Nevada, with fineexamples from both lode and placer deposits. In South Dakota, from the Homestake mine atLead, Lawrence Co.; in Colorado, wire and leaf gold from Breckenridge, Summit Co.; in Lake Co.,at Leadville; in Alaska, in lode mines in the Juneau district and placers along the Yukon River.
Near Santa Elena, in the Grand Savannah River region, Venezuela, a placer producing exceptionalskeletal crystals. A bonanza gold rush occurred at Serra Pelada, Pará, Brazil.
Name: An Old English word for the metal; perhaps related to the Sanskrit jval; chemical
symbol from the Latin aurum, shining dawn.
References: (1) Palache, C., H. Berman, and C. Frondel (1944) Dana’s system of mineralogy,(7th edition), v. I, 90–95. (2) Jones, R.S. and M. Fleischer (1969) Gold in minerals and thecomposition of native gold. U.S. Geol. Surv. Circ. 612, 17 pp. (3) Ewald, P.P. and C. Hermann,Eds. (1931) Gold, Au. Strukturbereicht, 1, 38–40 (in German). (3) (1953) NBS Circ. 539, 1, 33.
(4) Criddle, A.J. and C.J. Stanley, Eds. (1993) Quantitative data file for ore minerals, 3rd ed.
Chapman & Hall, London, 204.
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