In this edition we start getting into the good stuff, where we start processing gold. I'll talk about what tools you can use, how much they cost and how to use them. But first, I want to hear your stories. Have you found gold? Tell me about it. Send it to the Editor-In-Chief of the paper and I may use it in a future column!
Ok, what kind of equipment can you use to sample and process your dirt? It really depends on where you are and what type of deposit you are working, lode or placer. Since we live in the desert I'll focus more on dry methods. That is the bane of desert prospecting, the water...or lack thereof. Carrying a lot of water to the gold fields usually isn't an option, but you can carry enough to fill a panning tub for sampling. For processing you will need specialized tools.
One of the most popular processing tools in the desert is a drywasher. This machine works a lot like a sluice box in a river but uses no water, hence the “dry” in the name. It uses a regular looking sluice box with some distinct differences. One difference is that the riffles, the cross pieces that catch the gold, are reversed from a water sluice. Second, the bottom of the sluice isn't solid, it is usually some sort of perforated screen or mesh. Air is blown through this mesh from the bottom to agitate the dirt to let the gold settle. It uses a leaf blower or shop vac to provide the air. The action of the air movement also causes an electrostatic charge to be created which helps the gold separate. The recovery rate on a well setup machine can be as high as 95% or better, depending on how it is used.
You can build your own drywasher fairly easily or you can buy a commercial model. The price can range from around $100 for a DIY unit up to $500 to near $1000 for a commercial model. It is not cheap but it can process a ton of dirt quickly, which is what you want whether you are testing or processing. There are also drywashers that use a puffer system with a bellows that creates the airflow. These can be manually or electrically operated. These puffer types are not nearly as efficient than the blower types but will do the job.
Another tool also used frequently is sort of a crossover wet method. A mini highbanker is great for sampling in the field. The drawback is you have to carry enough water to operate it. Most can be used with just 5-6 gallons of water so it is not prohibitive, but needs planning. Once set up it is also not mobile, you would have to carry your dirt from the dig location to the unit for processing. The advantages are a much higher recovery rate by utilizing water and they are generally lightweight and portable. A DIY unit can be made for around $50-$75 and commercial units are generally $300-500.
Both drywashers and mini highbankers use a two sluice setup. The top sluice box is a simple hopper with a classifier screen to let only a certain size dirt/gravel to enter the sluice box with riffles. This classifying is crucial. A general rule of thumb on classifier size is to try and match the size of the dirt/gravel allowed through to the size of the gold in your area.
Metal detectors are probably the most used tool in a desert environment. They can be easy to carry require no water and are great at finding pickers and nuggets. Remember, though, there is far more fine flour gold than there are nuggets, so you are going to have to work. Another issue with detectors is you will always find a lot of junk; bullets, shells, foil, lead shot, beer cans, rusty parts of old machinery and more are all things you will have to dig up in your quest for the gold. It is also advised you dig up every target, especially for beginners. Metal detectors are a tool, not a guarantee. They can frequently give false signals, both positive and negative. They require a lot of patience and fortitude to keep at it, but the rewards can be huge.
Which detector you use is almost entirely predicated on your budget. You can get cheaper models from $50-100, or you can spend up to $10,000 or more on the higher end units. What's the difference? All metal detectors will detect all metal, it is kind of in the name. Actually they detect differences in electrical resistance, but that gets into the geek speech weeds and not relevant for our purposes. The main differences in all detectors are the bells and whistles with which they are equipped.
Some allow you to seek deeper, ignore certain ferrous targets and more.
There are two main divisions in the detector world; VLF and PI. VLF stands for “very low frequency”.
This type of detector will only punch a few inches into the ground but are very accurate on even the tiniest of targets. The smallest nugget I found with a VLF was only 0.7 grams, very small. PI stands for “pulse induction”. PI's can seek a lot deeper, sometimes even several feet into the ground, but they are generally not very good at finding those tiny targets. It really depends on the type and size of gold you are going after as to which will work better for you. Because of this there really is no “best” gold detector. I have found gold with a cheapo Radio Shack special and with my PI.
In my next article we'll go deeper into the processing arena. All of the tools in this article, except for metal detectors, are used to concentrate your raw dirt into just the heaviest of materials. These always need further processing, whether by panning or some other mechanical means.
As always, if you have questions, comments or your own prospecting stories, please submit them to the editor of this paper and I will get them. Until next time, happy prospecting!