We have seen many prospectors move a lot of material with minimal recovery during the years. Including ourselves on occasion. Why would someone process a large volume of material with nothing to show for it?
More important, how can you ensure you meet your expectations?
Properly test the area. Set up your equipment carefully. Practice until you have optimal operation. Go slow and be prepared to change tactics. Small changes in the set up of equipment can make a big difference in your recovery.
Test First: Gold will not be found in barren areas no matter how good or expensive your equipment is. The first step is to test your claim using a grid system or another method making sure to mark your test locations and/or record gps locations. Label the sample bags so you can track the location of the samples with the best results. Many people will set up their equipment at the first sight of gold, this is not what I recommend. You may be a few feet or yards from a hot pay streak that will yield 100 times more gold than the first test site. It is to your advantage to first extensively sample the claim. Work smart, not hard. I personally prefer small feeder gulches with patches of exposed bedrock, including cracks and crevices over large wide desert washes. Oftentimes in the large washes the sand is deep, to dig to bedrock requires moving an overwhelming amount of material.
Recently, we went out to a claim that had tested positive for gold. The guys set up the dry washer at a spot where a small gulch made a sharp turn. Two men began shoveling fine to medium size sand and gravel into the dry washer. Within about 4-6 inches they hit a layer of sticky clay. After several hours of picking and shoveling clay we dumped the cons and ran them through a Desert Fox Gold Wheel. Our results were disappointing, no gold. The next day I was checking the riffles in the gold wheel and there was a small amount of clay that had dried. I scraped out less than a thimble full and panned it recovering 6 small pieces of gold.
Where we went wrong: We didn't take time setting up our equipment and we were feeding the dry washer way to fast. The small particles of gold were sticking to the clay like black sand is attracted to a magnet. These small balls of clay, minus 1/4 inch were flowing down the riffle box like marbles on a sloped driveway ending in the waste pile along with our fine gold. Another, perhaps our primary issue is that we didn’t get to bedrock. Also, some of the lumps of clay were large and needed to be broken down to near the size of the pieces of gold that we were expecting to see. Same with our lead test. While it was performed with good recovery, we had bb’s smashed flat; much larger in size than we should have used.
One possible solution for processing the clay would be to dig up the clay and spread it out to dry in the sun before running it. The only efficient way I know how to break down large balls of clay is to first dry, then run the material through a small gas-powered impact mill. Ideally, this would break the clay down to the size of the gold particles you are expecting. Now the million-dollar question, is there enough gold attached or mixed with the clay to justify the extra effort and equipment?
I believe there is, especially if one reaches down to bedrock and works the cracks, crevices and fractures.
Mine Finder Gold