Showing posts with label gold prospecting. Show all posts
Showing posts with label gold prospecting. Show all posts

Saturday, August 12, 2023

GOLD, RUBIES, COPPER, and other TREASURES from the EARTH.

Unrefined native gold found on Rock Creek, 
South Pass, Wyoming (photo by W.D. Hausel)

The photos are mine: collected by earthly wisdom and given to me as a gift from God. 
But the words are not mine - they are 2,700 years old, and provide heavenly wisdom. Earthly wisdom may be good for some, but I would trade all for a little heavenly wisdom.

“Surely there is a mine for silver,
A mine for silver - ruby silver (reddish) in chlorite schist with
some sphalerite (zinc ore), and galena (lead ore) from the 
Mayflower mine, Park City Utah.


And a place where gold is refined.
Iron is taken from the earth,
And copper is smelted from ore.
Man puts an end to darkness,
Putting an end to darkness - Thomas prepares to take
ore from the darkness at Arizona's Resolution mine

And searches every recess
For ore in the darkness and the shadow of death.
He breaks open a shaft away from people;
Breaking opening a shaft - geologist stands
under square set on the 350-foot deep 
Carissa gold mine shaft, South Pass, Wyoming.


In places forgotten by feet
They hang far away from men;

Copper ore consisting of blue azurite, green malachite, and black
tenorite, Kirwin district, Wyoming (W.D. Hausel photo)

They swing to and fro.

As for the earth, from it comes bread,
But underneath it is turned up as by fire;
The earth is turned up as by fire - folded
banded iron formation in the Seminoe
Mountains greenstone belt, Wyoming, has
been squeezed, torn, and turned up.


Its stones are the source of sapphires,
And it contains gold dust.
That path no bird knows,
Nor has the falcon’s eye seen it.
The proud lions have not trodden it,
Nor has the fierce lion passed over it.
He puts his hand on the flint;
He overturns the mountains at the roots.
Overturning mountains at the root - the Bingham open pit
mine in the Oquirrah Mountains of Utah - a source for gold,
silver, copper, lead, zinc and many other metals has provided
for the miners of many generations.

He cuts out channels in the rocks,
He cuts channels in the rocks - exposing 'blue ground'
(weathered kimberlite) to find diamonds at the 
Aultman 1 kimberlite pipe in Wyoming.


A
nd his eye sees every precious thing.
Iolite (gem-quality cordierite), a beautiful blue, sometimes 
purple, sometimes lavender gemstone - a precious thing
found in the central Laramie Mountains of Wyoming.


He dams up the streams from trickling;
What is hidden he brings forth to light.”
“But where can wisdom be found?


Iron from the earth - specular hematite (botryoidal with 
limonite (yellow) and earthy hematite (red) from the
Hartville uplift, Wyoming.

And where is the place of understanding?
Man does not know its value,
Nor is it found in the land of the living.
The deep says, ‘It is not in me’;
And the sea says, ‘It is not with me.’
It cannot be purchased for gold,
Nor can silver be weighed for its price.
It cannot be valued in the gold of Ophir,
In precious onyx or sapphire.
Neither gold nor crystal can equal it,
Nor can it be exchanged for jewelry of fine gold.
No mention shall be made of coral or quartz,
For the price of wisdom is above rubies.
The topaz of Ethiopia cannot equal it,
Nor can it be valued in pure gold.”



Searching for rubies, I found them - right where they were 
suppose to be
. Ah, to be endowed in earthly wisdom - but I
would trade it all for a little Heavenly wisdom (photo by Hausel).

“From where then does wisdom come?
And where is the place of understanding?
It is hidden from the eyes of all living,
And concealed from the birds of the air.
Destruction and Death say,
‘We have heard a report about it with our ears.’
God understands its way,
And He knows its place.
For He looks to the ends of the earth,
And sees under the whole heavens,
To establish a weight for the wind,
And apportion the waters by measure.
When He made a law for the rain,
And a path for the thunderbolt,
Then He saw wisdom and declared it;
He prepared it, indeed,
He searched it out.
And to man He said,
‘Behold, the fear of the Lord, that is wisdom,
And to depart from evil is understanding.’”
A crystal from the Sierra Madre, Wyoming - a chlorite 
pseudomorph after almandine garnet.





Monday, November 11, 2013

Ore Shoots

What is an Ore Shoot? Some may think that ore shoots have something to do with guns. Not really. But it may be good thing to carry a gun in bear or mountain lion country when searching for ore shoots. Those bear can move almost as fast as my Honda Fit! An ore shoot is considered a minable part of a vein that has been enriched by one or more structural or chemical processes along a vein or lode - it is essentially the equivalent of a pay streak in a gold placer. After examining the definition reported by Wikipedia, Merriam-Webster, and Lexico, I can see why people get confused over this term, as it is apparent that these three sources on the internet have little understanding of ore shoots. Is it just me, or has the internet made a major dumb-down in the past few years. Seems like the internet is starting to Woke and get stupid, just like some of its human counterparts. Mindat is the closest to a good definition of ore shoot, but it needs a little help, and the Free dictionary is the best of these.

Ore shoots are those parts of veins, ore bodies, or mineralized faults that are enriched in mineral values such that it may be minable under favorable circumstances. Ore shoots are surrounded by vein or mineralized rock material of lower value, and can be structurally or chemically enriched, and can be formed of primary or secondary ore, or both. A similar term to 'ore shoot' is ore chute.

Many chemically formed ore shoots yield good ore deposits. During vein formation, hot silica (quartz-rich), hydrothermal acidic fluids react with rocks of favorable chemistry; particularly rocks with calcium carbonate (limestone, dolomite). Thus, while prospecting a vein along trend where it cuts through limestone, could lead the prospector to skarns, replacement deposits, etc in a search for gold, silver, copper and other valuable minerals. Replacement deposits and skarns are often formed when such mineralizing fluids come in contact with limestone or even rocks such as limy shales, or limy sandstones. Replacement deposits can be very rich.
Cupriferous gossan - note the tawny limonite (hydrated iron oxide) with fissures filled with azurite (copper carbonate) typically found in many mining districts in Arizona and Utah, particularly in
leached zones and also in supergene enriched zones. Such zones are commonly found associated
with copper ore in Arizona.

The tan matrix in this specimen invaded fractures in a quartz vein and partially replaced
the quartz.

Imagine you are mining along a mineralized vein for
galena (lead-sulfide), and the material is very low
grade, such as that at Black Buttes, WY (top photo).
Then, over a short distance, the vein is enriched yielding 
a massive galena ore shoot, such as that at the Emma mine, 
Utah (bottom photo).
 
A sample of massive galena from the Lark Mine, Utah. While 
searching for galena, a miner might discover that the
lead-sulfide contains silver within the crystal structure. This
would also improve the value of the ore (or ore shoot), but
the silver would have to be metallurgically extracted from
the crystal structure of the galena. Much galena is used to
manufacture bullets! So, how does one separate lead from 
sulfur, and how does one extract silver from lead-sulfide?





Thursday, March 28, 2013

Ore Shoots and How to Trace Lode Veins

The Duncan mine and mill as they appeared in 1977 (photo by Dan Hausel).
Prospectors need to focus on finding ore shoots in veins. Nearly all veins in gold districts will have some gold and silver, but the values are alway erradic. Thus if you were able to follow a vein for some distance you will likely find trace amounts of gold at most locations. When I mapped the South Pass greenstone belt and its more than 16-miles of gold-bearing shear zones and veins, it was quite noticable that the vein-shear zone structures had trace gold with periodic zones of highly enriched gold. In some cases, the gold was enriched as much as 100 to 1000 times that of the normal values in the shear-vein structures.

So, why did these ore shoots occur and how was someone going to be able to identify them without crawling across the 16+ miles of vein-shear structures and assaying every inch?  Unfortunately, its not so easy. And then there are large areas that are hidden under soil and aluvium that could easily have cover a very good ore shoot.

An example of a potential structual-controlled ore shoot. Note the fold in the rock. The folded structure in the lower photo is identified as 'folded ore shoot'. The 'nose of folds (ore shoot)' may be enriched in gold, as I found at the Duncan and Carissa mines at South Pass.

While mapping around the Duncan and Carissa gold mines, I found some ore shoots where the gold values increased dramatically. But what was causing this was not quite clear at first. These ore shoots were difficult to recognized because of considerable soil cover and also the rocks that hosted the ore shoots were all black amphibolites and it was very difficult to see entire structures. But at the Duncan mine, I was able to collect enough samples across the structure and was able to actually plot the gold value increases leading into an ore shoot. The values increased about 100 times the normal gold values.

It turns out that the high gold values I detected (a 2-foot long channels sample that assayed 1.06 opt Au) were part of an ore shoot that was structurally controlled by folding. While mapping the Carissa mine, I found this structure as also intensely folded. Gold values at the Carissa were enriched more than a hundred times the average of the shear structures in the district.


Copper (chalcopyrite) breccia from Wyoming. Note the
angular rock fragments
Next, let's look at this in three dimensions. Well we can't really, because all we can see is the surface exposure. But at the Carissa mine, the mine shaft was sunk to 450 feet and drilling intersected the ore shoot to depths as great as 970 feet giving us a 3-D perspective. Now imagine these folds are large round pipes (in case of the Carisaa mine, we are talking about a 1,000-foot diameter pipe!). Now imagine placing this pipe in the ground from the surface down into the earth so that it stands nearly vertically. This should give you a general idea of what these ore shoots look like. 

So, the Carssa ore shoot plunges down into the earth for at least 970 feet (that was the deepest anyone ever drilled in the district), but there is no reason to believe this ore shoot does not continue to the base of the greenstone belt (2000 feet, 3000 feet, 5,000 feet, 10,000 feet?). So, the Carissa likely has a very large gold resource - but it was withdrawn from mining - not by the Federal government, but by its evil twin - the State government (and all done quietly - like a ninja in the night).
The rocks at the Carissa mine are like an accordian - folded
and squeezed

Other ore shoots may form where there is considerable breccia, or an increase in open space by faulting or by a rising gaseous vent. So, breccias should be examined for enriched amounts of ore. There are many rich breccias that have been found in Arizona that are the result of high-pressure mineralized gases erupting from depth. Many such breccias have been found about giganic porphyry copper deposits.

Ore shoots are areas in veins where valuable mineralization increases, often dramatically. It has always been a subject of economic geology to try to understand where these rich shoots form and why, so miners can predict where the greatest amount of ore will be found in a vein, fault or shear zone.

Ore shoots can form chemically. During vein formation, hot quartz-rich, acidic fluids will react with rocks of favorable chemistry, particularly rocks with calcium carbonate (limestone). Thus following a vein in any area that may have limestone should lead any prospector to search the limestones for gold and other valuable minerals. Replacement deposits and skarns are often formed when such mineralizing fluids come in contact with limestone or even rocks such as limy shales, or limy sandstones. In some cases, the replacement deposits can be very rich.


Copper (green) breccia with common quartz prisms in vugs surrounding angular rock fragments.
 

Gold & silver rich quartz vein on the surface. This resistant rock outcrop of quartz can be traced from the camera and continues to the center of the photograph. Most veins are quite linear and can be traced on the surface for hundreds of feet and sometimes thousands of feet.