Mineral Information and Data:

Au [CNMNC approved formula]

Named from an Old English word for the metal; perhaps related to the Sanskrit jval; chemical symbol from the Latin aurum, shining dawn.

IMA status : Valid species (Pre-IMA Ancient) Grandfathered
(8th edition) :  
  (01) Native Elements
  (01.01) with metallic elements other than the platinum group
  (01.01.01) Gold group
(10th edition) :
  (01) Elements
  (01.A) Metals and Intermetallic Alloys
  (01.AA) Copper-cupalite family
Crystal system: Cubic System
Point group (H-M): m3m (or 4/m 3 2/m) — hexoctahedral
Unit cell: a = 4.079 วบ
Crystal Habit: Crystals octahedral, dodecahedral or cubic, flattened and elongated, dendritic; massive as nuggets, grains or scaled
Twinning: Common on {111}, generally repeated
Color: Gold-yellow with a reddish tint when pure, silver-white to copper-red when impure; blue and green in transmitted light
Diaphaneity: Opaque in all but thinnest foils
Luster: Metallic
Hardness (Mohs): 2.5 to3
Measured Density: 19.279 g/cm3
Tenacity: Very malleable and ductile
Fracture: Hackly
Streak: Same as color
Geologic Setting: 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.
Mineral Association: Pyrite, chalcopyrite, arsenopyrite, pyrrhotite, sylvanite, krennerite, calaverite, altaite, tetradymite, scheelite, ankerite, tourmaline, quartz
Ore deposits: The primary mineral of gold is the native metal gold.
Synonyms/varieties: Electrum (Ag-rich var.), Porpezite (Pd-rich var.), rhodite (Rh-rich var.)
Comments: Forms a series with silver.


Gold on quartz
Origin: Pamour Porcupine mine, Timmins, Ontario, Canada
Sample size: 18 x 8 x 8 mm
Photo: Dan Weinrich


Gold and sphalerite vein in quartz
Origin: #1 vein, 1913-Hollinger mine, Timmins, Ontario, Canada
Sample size: 2 x 2 x1.5 cm
Photo: Tom Loomis


(zoom-in of above)


Origin: Hollinger mine, Ontario, Canada
Sample size: 6 x 6x 3 cm, 7 mm gold crystal
Photo: Tom Loomis


(zoom-in of above)