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Electronic
Prospecting Device
For those who don’t have the time or inclination to learn to dowse
there are quite a few electronic devices available these days for
detecting gold deposits. Unlike dowsing though they are limited in
the depth, search area, size and type of targets that can be found.
One of the most popular types currently used is the Very Low
Frequency detector . They put out a vibrating magnetic field that is
influenced by any conductive metals that come within that field. The
circuitry of the detector turns that influence into an audio or
visual signal to let the operator know what is buried below the
search coil. The depth and size of gold particles is limited by the
strength and frequency of the magnetic field put out by the
detector’s search coil. In the hands of a skilled operator ‘black
sand’ deposit streaks, which may contain gold particles, can be
located as well as non-ferrous metal particles like gold. These
detectors have been developed from the first beat frequency metal
detectors invented during WW II to find land mines.
There are several other geo-physical prospecting aids for finding
placer gold deposits but this VLF type detector is the one presently
most favored by the placer nugget hunter.
Iditarod 'What If?'
When out prospecting with a partner sometimes in evening when
sitting back around the campfire we get to talking. This happened on
one occasion to me when up in the Bowron country. My prospecting
partner Dave R. and me were camped on Indian Point Creek. One
evening he got to talking a bit and he told me about a relative of
his who lived a little farther north in BC from where we were. This
relative of Daves used to supplement his income by trapping in the
winter. A few years ago, or maybe a bit longer than that, this
relative of Dave's decided he needed a dog team to run on his
trapline.Being a creative sort he got hold of a huge Great Dane
female dog. When this dog came into esterus he took her out into the
wilderness near his cabin and tied her to a fir tree. After backing
off about a hundred yards where he could watch the Great Dane he
waited to see what would happen. After four or so hours a wolf got
wind of the Great Dane , scented her condition and visited her.
Unfortunately after mating with the Great Dane the wolf tried to
kill her and Dave's relative had to shoot the wolf.
In the fullness of time the Great Dane gave birth to seven gangly,
raw- boned puppies, just right for the trappers dog team. That team
became legendary in that part of northern BC. No other team could
touch them for strength, speed or stamina. The trapper was the only
one to feed and care for them for others knew to give them ample
room. He put bells on their harness so you could hear the team
traversing BC's winter wonderland, loping by moonlight, devouring
the distances; from many kilometers away.
I sometimes speculate how that team would have made out if they had
been allowed to run the Ididarod: would they have made Susan
Butcher's team look like a bunch of fumbling puppies? (C.D.O.)
Postholeing
This is a prospecting method for locating ore veins. For use in
locating placer deposits it could be used to locate pocket deposits.
These would be colluvial placers from supergene enrichment. The
method could also be used to locate eluvial placers and to trace
'bleedoff' back to the bench deposit laid down by an earlier channel
of a gold bearing river that is now high and dry.
The Australian 'fossikers' call postholeing; 'loaming'. Here's what
the Australian Prospector's guide had to say about it:
Quartz Reefs
Loaming
Loaming is an old and well tried prospecting technique which may be
said to be the forerunner of the modern geochemical methods used for
prospecting for base metals.
as the name implies, "loaming" is essentially a soil sampling
method. In areas where alluvial gold has been known in the gullies
or where the prospector has other reasons to hope that gold reefs
might exist, systematic sampling of the hillside soils is undertaken
followed by panning of the samples to detect colors of gold. Very
fine colors may be significant and the panning has therefore to be
undertaken with great care and perhaps a magnifying glass used to
examine the heavy residues for gold colors.
A common procedure is to take a line of samples at one level on a
hillside from twenty to one hundred feet apart according to
circumstances. If gold colors are detected in some samples a second
line is taken above the area where the colors were located.
Repetition of the process may disclose a more restricted
distribution of the colors, becoming coarser as the prospector moves
up the hillside. Ideally the distribution becomes restricted to a
few feet and coarse colors, some of which may be still attached to
pieces of quartz, may be found at a point above which no gold colors
can be detected. Trenching in this locality through a foot or so of
eluvial material on the surface might be expected to disclose the
reef which has shed the gold.
In practice the pattern of colors found on a hillside may be
confused by the fact that a number of different sources have shed
gold and often the gold has come from extremely small veins which
have yielded the whole of their values to the loam. In this latter
case fairly good loams may be found without their source being
traceable.
It should be remembered that loaming is essentially surface sampling
and any values contained in loams have come from reefs or veins
occurring at a fairly shallow depth. There is usually no point
therefore in sinking trenches or shafts through many feet of
colluvial or alluvial material to find the source of loam gold.
In the field, the places at which loam samples are being taken are
often remote from water and the prospector has to carry his samples
back to a steam for washing. Various sample bags may be used for
this purpose, one common type being the loam bag which is a long
sleeve-like bag into which loam samples of the order of a pound or
so in weight are inserted and successively tied off in such a way
that the completely filled bag resembles a string of sausages. The
bag is carried slung around the shoulders after the fashion of a
scarf. The prospector should make a rough sketch indicating where
his samples have been taken and then transport them back to water
for panning off. The pan used is a small loaming pan about nine or
ten inches in diameter. A light pick and shovel is required and a
modern device consisting of a light folding combination pick and
shovel is an effective tool.
Although the results of loaming are often difficult to interpret the
method is an excellent device for prospecting and has probably been
responsible for locating the majority of reef deposits in Australia.
Some additional notes:
A pant leg with the end sewn shut makes a good loaming bag.
Chlorine bleach can be used to clean concentrates so the gold specks
show up.
Radio shack has both 30x and 100x magnifiers with light for about
twenty dollars per unit.
A company with deep pockets has a geologist with two prospectors
using this method in the area where my claim is. The prospectors are
given a grid to do their sampling from and the samples are shipped
to an assay lab in Kamloops. They then get instructions where next
to sample. One of the prospectors said they sample from 6 to 20
inches below the leaf mold section of topsoil. He said they use a
tower of classifying meshes to sort the soil sample and sometimes he
does see visible specks of gold in the samples. And you thought
prospectors didn't have to work hard!
Gemstones
In BC we have a sorry record when it comes to prospecting for
gemstones. The fixation in placer prospects, and each pan is a
prospect, is with gold? Gem values usually get tossed out. Here's
what the Australian Prospector's guide says about gemstone
prospecting:
Gemstones
Gemstone collectors will find that a knowledge of geology will be of
great assistance by providing an explanation of the manner of origin
of gemstones and the places in which they are found. There are many
varieties of gemstones and semi-precious gemstones which, in
general, are formed in any of three ways:
(1) Magmatic Minerals
These minerals crystallize either from liquid rock material called
magma, deep below the surface of the earth as granite rocks, or on
the surface as volcanic rocks. Since the elements which form many of
the gem minerals are present in the magma in small amounts only, and
do not crystallize at the same time as the normal rock-forming
minerals, these elements are therefore concentrated in the remaining
magmatic liquids. These liquids, which may eventually crystallize as
very course grained dyke rocks called pegmatites, are the richest
source of gem minerals.
Examples of magmatic minerals and their commonly associated rock
types are:
Basic and ultra-basic rocks (ie. those rocks with a low silica
content)-diamond, sapphire, ruby, olivine, garnets such as pyrope
and uvarovite.
Granitic rocks-sphene, zircon, quartz, feldspar, topaz, tourmaline.
Pegmatitic rocks- emerald, beryl, chrysoberyl, cordierite, feldspar,
garnet, kyanite, quartz, sapphire, ruby, spinel, spodumene, topaz,
tourmaline, zircon.
(2) Metamorphic Minerals
Metamorpic Minerals and rocks are those that have recrystallized
from pre-existing rocks under the influence of terrestrial heat
and/or pressure. It is possible to recognize two types of
metamorphism- contact metamorphism which occurs adjacent to deep
seated igneous rocks such as granite where the main influence is
heat, and regional metamorphism where the main influence is
pressure.
Examples of gem minerals formed by metamorphic processes are:
Contact metamorphic limestones and marble-ruby, sapphire, corundum,
emerald, garnets, scapolite, epidote, tourmaline, sphene.
Regional metamorphic schists and gneisses-corundum, spinel, garnet,
tourmaline
The minerals jadeite, nephrite, serpentine, and steatite probably
represent highly metamorphosed ultra-basic igneous rocks.
(3) Minerals formed by Aqueous Solutions
These are minerals formed at a later stage than the enclosing rocks
and have been precipitated from circulating aqueous solutions. The
solutions may represent either very late stage magmatic
(hydrothermal) solutions or circulating ground waters. Both these
solutions may have very similar compositions which would result in
the formation of the same minerals.
Typical hydrothermal minerals are:- Many varieties of quartz, agate,
jasper, opal, topaz, chalcedony.
Typical minerals formed from circulating ground waters are:- Opal,
agate, chalcedony, turquoise.
In most cases the gemstones are present in the original rock in very
small amounts only. As the rocks are frequently very hard, it is
virtually impossible to recover the gemstones economically without
damage to the stones. Since the gemstones are by their very nature
usually highly resistant to weathering, they are thereby freed from
the less resistant rock. The weathered material may be transported
by water and the gemstones because of their resistance to abrasion
and generally higher specific gravity, may accumulate and become
concentrated in gravel deposits. These gravel (placer) deposits are
usually richer and more easily worked than the original deposits,
and the gemstones are generally of better average quality than those
in the primary deposits because of destruction of flawed and cracked
stones. Soft gemstones such as opal do not withstand the continuous
abrasive stream action and these minerals must be mined from the
enclosing rock.
Most gemstones are found
in gravel or placer deposits and it is in this type of deposit that
a search should be carried out. These gravel deposits may be in
present day stream beds or represent ancient stream deposits.
A knowledge of the origin of gemstones coupled with a knowledge of
the geology of the area is therefore useful in gaining an indication
of the type of gemstone most likely to be found there.
Streams flowing off granitic areas will contain granitic and perhaps
pegmatic minerals such as quartz, beryl, tourmaline. Streams flowing
from metamorphic areas will contain typical metamorphic minerals
such as garnets and corundum; and streams flowing from areas of
volcanic rocks, particularly rhyolites will frequently contain
considerable quantities of chalcedony and agate.
Additional notes:
An ultraviolet light can be handy for examining pan concentrates for
sheelite crystals and zircons.
Save the gray sand as well as the black sands. The heft of most
gemstones is in the area of the gray sands.
Practice examining the pan concentrates for gemstones. Let's quit
throwing the gems away!
Recreational Prospecting Trip 2005
Overall...had a great trip. Jerry and I went up to the Horsefly area
first, and did some panning at Squaw flats on the horsefly
river.........just very few pieces of powder per pan. but ..a fella
came there, and as usual I got talking to him, and he said he had
gold on his place we could pan, on the same river, but further up.
Jerry and I gave it a try, and wow...it was good...nothing that huge
to be called a nugget...but it sure did add up quick. (but had lots
of mercury on it) In 6 hours, I panned out as much as I did all one
summer going out every weekend...so of course, I thought that was
great...but we had to move on to our next destination.
We went to Likely next...very small but pretty area, and after a few
initial pictures taken, headed to our destination of Quesnel Forks,
a ghost town...loved it there, but they sure got some dummies
camping there I hear. They are trying to rebuild some of the
buildings, and on a weekend, someone came in and with a power saw,
sawed up one complete wall into one foot chunks for
firewood.....another weekender burnt a complete wall for a fire pit
fuel. Sure is hard to get ahead of reconstruction that way..and no
one to watch over it all on weekends. Weekdays, there are the
workers there, and they always dread what they will find come Monday
morning. One of the fellows in charge, quite interesting to talk to.
Anyone with pics of Quesnel forks before 1960..please send on to me,
as he has no email, and sure would appreciate some if you have them.
Tried my hand at panning...thought it was just so-so and around
water, I can always find other things to do...so took a nice good
lea surly bath and washed my hair their... then did some good old
fashioned fishing... and yes, caught nice trout and ate it for
supper. Got some good pics, and a video clip of Jerry doing his sock
laundry in his gold pan (isn't that what the riffles are for??? lol)
Beautiful weather so far for us, so made the holiday trip much
nicer. Jerry did a days panning, said the gold was finer, and not
much of it...but stuck to it, so has a descent sample. We stayed 2
nights there, so beautiful, where the two rivers meet.
Donna S.
THE "NATURAL
SLUICE BOX"
A PREDICTIVE MODEL FOR FINDING NUGGETS
For the VERNON PLACER MINERS'
ASSOCIATION
By George Addle, PEng,(BC) FGAC
February 1, 2005
The "Natural Sluice Box~~ A Predictive Model
Why Models? .....We have models for just about all metal mineral
deposits. The B.C."Geological Survey Branch" has been in the
forefront of developing them. In time these models become
"predictive". In B.C. Open File1995~20 there is a very good
"profile" of Surficial Placers by Dr. Victor Levson
Why Nuggets? .....Hand panning is allowed almost anywhere in British
Columbia. One does not have to worry about "designated areas" or the
priorities of fish in the creek. But a "predictive" model for
nuggets is needed.
Characteristics of a sluice box:
1. Slope of three to five degrees.
2. Width: Narrow compared to length.
3. Enough water to cause stratification.
4. Matting: Try "V" rubber matting. (10 per inch.)
5. Production: The more you move the more you make.
Theory of Stream Profiles:
In theory every stream has one hydraulic profile and one location
with a five degree slope. A "Natural Sluice Box Slope". Actually as
you can see from our maps there are a number of five degree slope
locations. Why? This may be because of a number of changes of "base
levels" due to a junction with another stream, a lake, or even a
change of basement rock type. A fault will also change the base
level. And of course there are man made changes such as dams.
Slope calculations for maps made for this course.
The contour interval is 20 meters.
The tangent of five degrees is 0.08749. (The sluice box slope.)
Question: With a contour interval of 20 metres and a slope of five
degrees what is the associated horizontal distance?
Answer: Divide the contour interval (20 metres) by the tan of 5
degrees. This gives
228.6 metres.
Question: Using a scale of 1:10000,
what is the 228.6 metres on our map?
Answer: Divide 228.6 metres by 100 metres and the result is 2.286
centimetres.
(Remember 1:10000 means one centimetre on the map is represented by
10,000 centimetres on the ground, or 100 metres.)
Width: The width of the natural sluice box must be narrow. Canyons
are the
nugget factones.
Amount of water: The amount of water must be enough to cause erosion
and not deposition.
Floor of a 'natural sluice box'
A schist, slate or shale is usually necessary. Note: In both the
Klondike and Barkerville, schists form the basement. Some dykes such
as Lamprophyre erode easily and can form traps. Other hard dykes
such as Alaskite may form ridges which are also traps. And of
course, faults can cause traps.
Difference between a sluice box and a "natural sluice box"
In a sluice box most of the gold is concentrated in the first six
inches. But In a "natural sluice box" the whole box may contain
nuggets. The canyon is then described as a "jewellery shop". In many
cases the nuggets are concentrated at the end of the canyon where it
opens up. This is called the "Debouchment"
Predictive targets for nuggets using topographic maps:
1. Natural Sluice Boxes
2. Canyons
3. Debouchments
My gold size classification:
1. If I can pick it up with my fingers, it is a nugget.
2. If I need tweezers the particle is a colour.
3. Everything else is micron~goId. Also known as "fly-specks".
A look at the morphology (form) of gold nuggets.
Look at the picture of the Yukon
nuggets. The nuggets are made by cold-welding of smaller nuggets.
They are probably bedrock nuggets. On the other hand look at the
Pend Oreille nuggets. They are flat, smooth, and highly polished.
This is flood gold, and may or may not be on the bedrock.
Some concepts from Geomorpholoqy:
(The science of scenery)
Lobec, 1939, uses the concept of young, mature, and old streams. A
young stream has a V" shaped valley and is relatively straight and
is down cuffing For our purpose it will be closest to bedrock. A
mature stream has meanders and neither erodes nor deposits. This
equilibrium is hard to maintain. If there is an increase in volume
of water the valley walls will be eroded. The valley itself is "U"
shaped and inour area is likely to be due to glaciation. In an "old"
stream the width of the valley is several times the width of the
meanders. There is no down cutting and material is being deposited.
Again the valley profile will be a large "U" shape. If glaciers have
been present it is possible that they plucked out a basin in the
valley. Which of course will be full of gold! a shaft of fiftytwo
feet? (Think "Barkerville". Is this why William Barker had to sink a
shaft of fifty-two feet?)
Remember, all rivers are due to differential erosion.
Dream
I believe there is more gold in the creeks and rivers of B.C than in
all the gold mines put together. Go for it!
Forward looking statement:
Until we get the results from next summer's prospecting I would
guess that the odds of finding a bonanza deposit with nuggets are
1/100 using the "Natural Sluice Box Model".
Recommended Readings:
1. "Geomorphology", by AK. Lobeck, (1939), from Amazoncom
$10.53US.
2. "Things Maps Don't Tell Us", by A.k. Lobeck, 1964. Amazon.com
$22.50 US
3. Everything you can find from Dr Vic Levson of the Ministry of
Energy and Mines of B.Q.
4. Everything you can find from Mr. Bill Barlee.
Where's
the Fountain?
For years I've heard about the fountain when researching possible
gold deposits along the Fraser River. At first I thought the early
prospectors were referring to the Nichoman River where it shoots out
high above the canyon to cascade down to the Thompson River. A few
days ago I was told about a bench along the Fraser River between
Lytton and Lilloet. The trail along the river followed this bench.
On both sides of the bench, upper and lower, there is, apparently,
steep slopes full of little creeks that roll down making a huge
natural fountain area. It sounds like a fascinating place. I hope to
see this before drive my ATV up the tricky trail through Hades. If
anyone out there knows anything about the 'fountain' that early
prospectors referred to would you please let me know-Cal Olsson.
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