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Although these tips are geared more towards
prospecting for lode gold, they are still of great
use to the electronic prospector, as almost all
placers deposits are derived from the erosion of
gold-bearing lodes. Being able to quickly identify
these favorable geological indicators will help you
narrow down your search and put you that much closer
to those nuggets!
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Favorable Areas: |
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1. |
Probably the most favorable area in which to
prospect for gold is one where the country
rock is made up of surface flows, sills,
dikes, and other intrusions of relatively
fine grained, light colored, Tertiary
igneous rocks such as rhyolite, trachyte,
latite, phonolite, and andesite. |
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2. |
As already been suggested, prospecting in
areas where there are outcrops of granitic
or schistose rocks that are cut by dikes or
other intrusions of relatively fine grained,
light colored igneous rocks may prove
profitable. |
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3. |
Areas in which the country rock is some type
of porphyry, especially if several varieties
formed at different times are found there,
may contain deposits of gold that can be
worked profitably. |
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4. |
Gold lodes that may be worked profitably are
sometimes formed around the borders of great
masses of granitic igneous rocks, both in
the granitic and in the surrounding rocks,
but more commonly the latter. |
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5. |
Areas in which some gold has already been
found are naturally more favorable than
places that have never produced any gold.
This statement applies particularly to areas
where considerable prospecting has been done
– any area in Continental United States
excepting much of Alaska. |
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Unfavorable Areas: |
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The saying that “gold is where you find it” is
certainly true. There are, nevertheless, certain
conditions that are so unfavorable to the occurrence
of gold in any considerable quantity that
prospectors would do well to avoid areas in which
these conditions exist. Among such unfavorable areas
are the following:
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1. |
Areas where large masses of granite and
related, coarse grained, crystalline igneous
(once molten) rocks outcrop, particularly if
these outcrops are not cut by dikes or other
intrusions of finer grained, usually light
colored igneous rocks such as porphyry,
rhyolite, or andesite. |
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2. |
Areas where large masses of gneisses and
other crystalline schists outcrop unless
they are cut by or in the vicinity of dikes
or other intrusions of igneous rocks. |
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3. |
Areas where large masses of sedimentary
rocks such as limestone, sandstone, and
shale outcrop unless they are cut by dikes
or other intrusions of the relatively fine
grained, light colored igneous rocks
previously mentioned, and, even where so
cut, sedimentary areas rarely contain
workable quantities of gold unless the
sediments have been metamorphosed (changed
in character by pressure and heat) to
marble, quartzite, or slate. |
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4. |
Areas where large masses of dark colored,
relatively heavy igneous rocks, such as
peridotite, diabase, and basalt or malpais
outcrop. |
It is not true that valuable gold lodes never occur
in areas described as generally unfavorable, such as
in a great mass of granite without intrusions of
other igneous rocks, for instance, but a prospector
will usually save time and money by avoiding such
areas.
* Information taken from: Arizona Lode Gold Mines
and Mining, Part II. Some Hints
on Prospecting for Gold,
by G.M. Butler, pg. 195. |
