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Gold-quartz placer nugget (derived from auriferous Precambrian basement rocks; Elk Creek, west of Rt. 285, southeast of the town of Lead, northern Black Hills, western South Dakota, USA) 1 | by James St. John
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Gold-quartz placer nugget (derived from auriferous Precambrian basement rocks; Elk Creek, west of Rt. 285, southeast of the town of Lead, northern Black Hills, western South Dakota, USA) 1

Gold-quartz placer nugget from the Black Hills of South Dakota, USA. (1 cm across at its widest)

 

This is a modern fluvial pebble composed of native gold (Au) and quartz (SiO2). The gold is ultimately derived from auriferous Precambrian basement rocks in the area of Lead, South Dakota. The now-inactive Homestake Mine, America's largest gold mine, is located in Lead (pronounced "Leed").

 

Gold masses that accumulate in river or stream gravels, or get trapped in fractures in bedrock-floored rivers, are called placer deposits - such gold is called placer gold.

 

Locality: attributed to Elk Creek, west of Rt. 385, southeast of the town of Lead, northern Black Hills, western South Dakota, USA.

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Photo gallery of gold:

www.mindat.org/gallery.php?min=1720

 

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Taken on July 3, 2012