The topic of black sand comes up in prospecting sometimes more than gold does! And it is very misunderstood. You often read or hear that the presence of black sand in an area means there is gold in the area also. This is not true. The presence of black sand means there is heavy mineralization in the area.
I know of several places that are loaded with black sand but have no gold. I also know of several places that have a good amount of gold but very, very little black sand.
You have to learn to use black sand to your advantage. When you walk down a wash and see streaks or deposits of black sand on top of the ground you can be certain the flow of water from the last storm deposited these streaks there. This means that the heavier minerals (maybe gold) most likely followed the same path. Sometimes when I locate an area with a heavy top showing of black sand I move just to the sides of the black streak, dig down about a foot or two and look for layering of black sand along the sides of the hole I just dug. This shows me that the black sand has been accumulating in the wash for a period of time. Which MAY mean gold has also. It may also mean it rained heavy, stopped, rain heavy again and so on.
Of course if I hit bedrock quickly I look for cracks and potholes to clean out. I usually dig a test hole every 20 feet for 200 feet. If I get nothing personally I move on. If I get some color in several holes I make an imaginary line from one good hole to another and work the imaginary line. This has been a very successful method for me.
In the photos at left I show how you can make a low cost black sand separator. This separator (mini sluice) is for small amounts of black sand. I run large drywasher and at the end of the day I have a lot of pure black sand concentrates and gold and use a spiral panner to separate that kind of a large amount. But for small amounts this mini sluice will do the job excellently.
You'll need a gold pan, about 2 feet of ribbed rubber mating from ACE Hardware, two clothes pins, a spoon, a sniffer bottle, and a garden hose. Easy stuff.
Make a U shaped channel out of the rubber mating. Secure it at both ends with the clothes pins. Put the garden hose at one end of the mini sluice and the pan (notice where the pan's riffles are) at the other end.
Take the teaspoon and begin feeding the mini sluice.
You can either use the sniffer bottle to grab the gold as you see it or wait till you have processed all the material.
Just remember experiment on the angle of the sluice vs. amount of water flow to get it right so you do not wash any gold into the pan. Even if you do you'll have the ridges in the right spot so you will not lose it.
I often run my finger over the ridges after I am done with the water flowing and move along any stubborn pieces of black sand that made be hiding small flakes of gold.
Best of luck...Rod