When it comes to gold mining, most get the yellow metal by sifting through sands and gravels along rivers and streams. This is called placer mining. It is due to the geological age of the earth that this is even possible. All gold deposits started as hardrock formations...and stayed that way until there were earthquakes, rivers, glaciers, tidal waves and a lot of earth movement which eroded mountains and ground down the rock into it's smallest form; dust. Trapped in all this rock were veins of gold, typically in quartz. These veins were also pulverized down into small pieces in nugget, flake and flour size. Because gold is so heavy, it settles to the bottom of our rivers, streams and any deep depression or crevice. This is where placer mining comes in. When we sift through all this sand and gravel to separate the gold, we are actually looking back at the earth's history.
The quickest way to reach this heavy mineral is to go deep and that is the hardest thing we could possibly do. Most placer gold is found within 50 feet of the surface of the ground. That's the "easy pickens". It is all the piles of gravels and sand we have to move first before we can reach the heavy nuggets. All this unwanted material is called "over burden" and it is the over burden that will make or break a mine. There are some very rich areas containing coarse gold that travels for miles following the bedrock of the earth, but there are just too many feet of rock and assorted mineral debris sitting on top of it to make it worthwhile to mine. This is just one of the reasons I am developing the deep gold drill to reach these zones of wealth that no one else can reach.
These golden rich layers vary in thickness from 18" down to a thin hair like trace. If we were to trace back to where these layers started from, it would be an intrusive outcropping of very rich veins that have been crudely eroded and strewn across bare rock or been given enough time to settle to bedrock. Glaciers and tremendous earth movements have left these rich zones buried deeply with over burden. California has one of these very rich areas. The surface of which has been the ancient streambeds that were worked in the gold rush of 1848 to 1855 (1849 being the height of this rush). These semi-surface ancient streams were often mined with hydraulic mining techniques. These mined areas often had 40 feet of unwanted rock sitting on top of them and were up a mountain side nowhere near water. That is one view of where gold is. The other is the heavy rich layer that sits on bedrock down deep under the earth. Some of these bedrock areas were accessible by miners usually by diverting rivers and digging down to the heavy layer.
Every method was employed to extract the wealth. Gold panning, sluicing, dredging and hydraulic mining were all used to good effect. Some outcroppings of hardrock gold were also found. At the time, crude attempts at crushing this mostly quartz rock were used to try to free the yellow treasure from the parent rock formations.
This crushed slurry was washed into massive sluice boxes and a lot of gold was captured. Using this early method only captured about 70% of this mineral wealth. The rest ended up in huge tailing piles left behind by these stamping mills. Early "worked areas" can be successfully re-mined using the cyanide process for complete removal of all gold still held in the waste rock.
Miners in the gold rush of 1858 in Barkerville, British Columbia often "drifted" down to bedrock, extracting huge quantities of coarse gold by tunneling along these rich placer deposits and simply follow the golden highway wherever it went. These drifts were only 40 feet down, the depth of gravel sitting on top of most rich bedrock areas starts at 40 feet and goes to several thousand feet.
There have only been a few REAL innovations in the gold mining community in the past two hundred years.
1) Suction Dredges:
Advantages
1) High processing capacity.
2) Much easier than using a shovel.
3) Works under water.
4) Cleans to bare rock.
Disadvantages
1) Illegal in many States.
2) It can wreck the environment if used irresponsibly (lay waste to fish spawning area) although most miners use dredges responsible.
3) You can only use it under water.
4) You can't work some rich waterways due to the current and other hazards.
Gold Suction Pumps:
There are many scenarios where one of these pumps can multiply the amount of gold you will take home. This type of gold pump has changed the way placer mining is done. It has also changed the volume of yellow wealth you can easily recover in a short time.
Lastly, the other major improvement in discovery and removal of coarse gold has been:
Metal Detectors:
Advantages
1) Relatively fast.
2) Good at finding heavy large nuggets.
3) Works wet or dry.
4) Don't need a lot of extra equipment.
Disadvantages
1) Always seem to need more batteries.
2) Can't easily "look" under water and pockets between rocks.
3) Relatively fragile.
4) Will only detect nuggets on the larger size at any distance of depth.
Check for black sand and iron pyrite (bring a magnet). Find a new gold location and stake a claim.
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A Brief Background
Gold can be found free in nature, but, is usually associated with silver, quartz, calcite, lead, tellurium, zinc and copper. Sea water contains approximately one milligram of gold per ton of water.
Gold is the most malleable and ductile of all known metals. One ounce of gold can be worked into a sheet measuring five meters flat. Gold can be flattened as thin as .000127 millimeters or about 400 times thinner than a human hair.
Pure gold is soft and usually mixed with other metals like:
- silver
- copper
- platinum
- and palladium
to increase its strength.
The amount of gold in the mix is measured with a unit called a carat. A carat is equal to one part in 24, so a 14 carat gold ring contains 14 parts pure gold and 10 parts other metals.