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Sunday, November 28, 2010

Trace Minerals found with Gold

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There are many minerals that are found in nature with gold, one of the most common found in placer deposits is small grains of magnetite.  This and other minerals have been used to find gold that can be recovered by the use of the pan.  Other minerals have been used in locating gold in lode deposits.  It seems that gold is often found with other metal bearing minerals including iron. These are called indicator minerals.



Fig. 1 Crystalline gold


Placer deposits are made from the products of erosion if they can withstand the rigors of the weathering process.  Very few minerals are hard and tough enough to survive whole and remain recognizable when they have been reduced to the size of sand grains, around 2 mm in diameter.  The most abundant mineral found in sand is quartz, SiO2 also known as silica. 

Quartz grains along with other minerals having a hardness of 7 or more on the Mohs Scale of Hardness make up what are called black sands or stream heavies in placer deposits.  Gold is another mineral found in the same environment that doesn’t depend on its hardness to survive in such an environment instead quite the opposite is true.  The ability of gold to survive is its softness and malleability allowing it to survive in placer deposits.

Most of the indicator minerals for gold are . . .

Quartz
Magnetite (Magnetic)
Hematite
Garnet
Beryl
Corundum
Feldspar (Sometimes)
Kyanite
Sillimanite
Topaz
Tourmaline
Mica (Small flakes)
Diamonds
Monazite
Zircon

There are others in the list, but these are the most likely to be encountered.


Lode gold is found in solid rock that is often discovered by tracing placer gold back to its source often using the indicator minerals found associated with gold in the gold train, a scattering of gold found away from its source rock.  The further away gold is from its source the smaller the particles become and the more widespread the individual particles of gold become.

Fig. 2 Gold in quartz

Most gold is found in quartz veins where it has been deposited from hydrothermal waters into the older quartz veins.  Much gold has been found in iron pyrite as a contaminant, and ever rarer it is sometimes discovered a “telluride” where it is combined with the element tellurium.

Many of the same minerals as found in sand can also be found in occurances of lode gold, but there are several other minerals that are just too soft to survive the rigors of weathering, they include . . .

Apatite
Calcite
Biotite Mica
Galena
Sphalarite
Chlorite
Feldspar
Staurolite
Arsenopyrite
Amphobolite
Garnet
Iron Pyrite
Pentlandite
Argentite
Granular Magnetite


These are the most common minerals associated with lode gold; there are others. 

4 comments:

  1. Going out for the First time today to Azuzsa Ca. with my 10' and 14" pan and most of what I need. and my Book on Minerals ans rocks. But I needed to know
    Q. What minerals found when panning for gold.
    Found it here Thank You. I will update you on my day. (Seen tones of YouTube videos to help me) Poco Zocko Actor

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    Replies
    1. PS. The Phoro above Linda Looks like Round Mounton NV. Where my Brother works

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  2. So is what your saying is, if im finding quartz in my creek and around my land i most likely have gold somewhere here?

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