Where to look for it:
Gold is much heavier than other materials and will come to rest when the current slows along the inside bend of the river or hits a major obstacle such as a boulder. Prospect thoroughly where a stream enters a lake. If you find any color at the mouth of a stream, chances are there is more gold further up the stream.
Streams that are most likely to contain gold must have two characteristics:
1. They should be undammed so that spring floods churn up heavy minerals which then get trapped below rapids, waterfalls and white water. Slow, meandering streams lost their gold far upstream.
2. They should be in a mineral-rich area (quartz, feldspar, black sand, etc.), not sedimentary.
Placer gold settles in specific areas of a streambed called pay streaks where the water flow slows down significantly after the spring floods, usually well upstream from the summer level. They may also form along the shortest, straightest path down the streambed at high water. When looking for a good place to search, visualize or actually view what the river looked liked during the flood.
Obstacles include bedrock ridges and large fallen trees, especially in the shortest, straightest path down the streambed. The best rock formations are exposed bedrock with small, near vertical fissures. Smooth, well-worn bedrock is almost never productive.
Where to look for gold:
- Gravel bars usually found on the inside of the river bends - especially newly formed.
- Where streams level out after a steep drop downstream of rapids or waterfalls.
- Small streaks of gravel lying on bed rock; if submerged, you will need a sucker to retrieve it.
- Downstream sides of large boulders and other obstacles which because of size or other factors appear to have been there for a long time.
- Pot holes or cracks in the bedrock. Large, obvious cracks have most likely been cleaned out many times, so look for lines of moss running along the bedrock; the small crack under the moss can contain gold.
- Highbenches. As a stream cuts deeper into a canyon, it can leave patches of gravel high on the canyon wall. These are called benches. Rounded rocks well above the present high water level have lived in a river at some time in their lives; these are the most likely places to find gold.
Black Sand Separators
Spiral wheels and the Blue Bowl along with separators will help you deal with it without a lot of tedious panning.
Put about ¾” of wash dirt into a black plastic gold pan. Rest the pan in water and rake your fingers back and forth to loosen and separate the material. With the riffles away from you, tilt the pan forward and rake coarse material toward you and discard it. Shake the pan from side to side to help the heavy minerals settle to the bottom. Repeat these steps until the coarsest material is gone.
Tilt the pan in the water so the fine material accumulates at the pan’s edge. Remove from water and tilt back, then forward, allowing a wave to carry the top material out of the pan. Shake the pan from side to side again, place it back in the water and tilt, so the light material remains just under the pans edge. Repeat using gentler motion until only fine material remains in the pan.
Finally, swirl the remaining material so it fans out to display any gold specks. Black sand (iron ore concentrate) can be easily removed with a small magnet. Collect gold specks with a damp finger and place them in a water vial.
Processing black sand (concentrate) can be done with a pan, a "Micro Sluice," a spiral gold wheel, or a blue bowl. The micro sluice is slow and winds up with black sand with the gold, but a spiral gold wheel will process 50 pounds of concentrate an hour and give you perfectly clean gold!
Black sand concentrates are a combination of hematite, Fe3O3 (SG 5.26) and magnetite Fe304 (SG 5.20); gold has a specific gravity of 15-19.3, making it easily recovered from the concentrate. Start by classifying the concentrate through a 10 mesh screen and run it through a spiral gold wheel, then through a 40 mesh screen, and rerun again.
Using a surfactant like Jet Dry® at the rate of three drops per five gallons of water prevents gold from floating out of the wheel. The tilt of the wheel should be 45 degrees to start, with water flow adjusted to an even flow without splashing, and the black-sand pyramid adjusted to an inch below the center hole. Adjust the tilt, not the water flow. Check the gold cup for black sand and re-adjust the wheel if necessary. It is possible to recover over 90% of the gold in the concentrate if the wheel is properly set-up and the concentrate is properly screened.
The new age of computer-designed gold wheels with built in agitators are well worth consideration. The new agitator wheel, turquoise in color, will fit most all older 13" gold wheels and pay for itself in short order. Also available is a micro adjuster for the older 13" gold wheels that allow micrometer-like adjustment for near perfect gold recovery.
The Blue Bowl
Of all the black sand separation methods, the Blue Bowl will probably save the finest gold without resorting to mercury or other chemicals; they work best with material that will go through a 20-30 mesh screen.
A 12” plastic colander, an 11” splatter guard with 28 mesh, and a 12” plastic pail were obtained for $1 each at Murphy Dollar Tree.
Rolling your own
The simplest classifier is made by drilling ¼” or 1/8” holes in the bottom of a plastic bucket. But if you want to use hardware cloth for a screen, cut the bottom off a five gallon bucket about an inch or two below the ribs; use the bottom of the bucket as a form to bend the screen. Prepare enough screen so that it will hang about 7” above the bottom of a second (nesting) bucket and cut off screen corners to accommodate forming. When cutting the screen wedges, leave some stubs on the edges of the screen so you can use long nose pliers to bend the stubs around adjacent parts of the screen to “sew it” together. Attach the screen to the top part of the bucket with flat-head screws or pop rivets. Attach two opposing handles via pop rivets to the classifier to make it easier to maneuver.
Fill a bucket with water and mount the classifier in it. Shovel 2-3 heaping loads into the classifier, then alternately lift and twist the material several times. Dump the classifier and repeat until you have enough classified material in the bucket. Dump the classified material into a gold pan.
Sluice boxes will generally move about ten times more classified material per hour than a pan. Find a shallow place where the current is moving fairly fast and can provide about a two-inch depth in the box at both sides (a twig should move through the sluice in about one second). You can build a little dam to direct the water into the sluice or to slow the current down (bypassing the sluice). Make sure that there is enough depth or current at the end of the sluice to carry away the tailings so they don’t accumulate.
When it is adjusted properly and level, a shovel full of dirt should wash through from the top of the box, leaving about 1/3 of its material between the first and second riffles for 30-45 seconds. Too slow and the gold won’t separate; too fast and the gold will wash away. Feed the sluice a half shovel full at a time to let the riffles clear. Place a heavy, flat rock atop the sluice to keep it positioned.
Clean the riffles at least once per day (more often on small sluices). Fill a bucket with water next to the stream. Lift the sluice box out of the water and keep it level; set the tail end of the box in the bucket, unfasten the riffles, roll up the carpet and slide it into the bucket. Using a gold pan, dip water out of the stream and rinse the material left in the sluice into the bucket, then unroll the carpet while it is in the bucket and slosh it around until it is clean. Process the concentrate.
Using the Sluice
Find a place where the current is moving swiftly and set the sluice directly in the current so that the box is filled with water almost to the top of the trough. A handful of light gravel should wash down the trough within a few seconds. Brace your sluice box so it doesn't rock; the incoming gravel should secure it.
Feed the gravel into sluice in regulated amounts that don’t overload the riffles and lose the gold; the tops of the riffles should be visible at all times.
Remove hung-up rocks immediately or they might lose concentrate. .
When the riffles have accumulated black iron sand extending more than halfway toward the next lower bar, it’s time for cleanup. Carefully lift the sluice box, keeping it as level, and carry it to the bank to set it down. Remove the riffle section of the sluice without disturbing the gravel adhering to it. Roll up the matting and place it in a deep bucket, then thoroughly rinse off all the concentrate. Rinse the riffle bars and the trough in the bucket as well.
Pan out the concentrate.
The typical wooden homemade sluice is made of boards from 8”-18” wide, 6”-12” deep and 3’-6’ long. Riffles made of half-inch square dowel can be nailed every 6” along the sluice bottom, with about a foot left at the top to receive material.
Although this type of sluice box does catch gold and is easy to build, it is hard to clean out at the end of the day, wooden riffles get beat up by gravel over time, and the wood gets waterlogged, increasing weight. Aluminum is preferred.
Excellent wooden sluice: http://www.mdpub.com/sluice/index.html
Remove the riffles and carpet; roughen the upper, uncovered surface with steel wool, clean it with paint thinner, then spray with several coats of flat black so that gold flakes can be more easily seen.
Unless your sluice already has it, get some black-ribbed rubber floor matting (about 8 ribs per inch) and a can of 3M 77 spray contact cement (or the cement that attaches vinyl tops to cars). Again, roughen the surface with steel wool and clean it with paint thinner. Mask off the vertical sides that you don't want covered.
If your sluice box has an attachable flair, apply the cement per instructions to the bottom of the matting and to the flair piece. Cover the whole flair with the rubber with the ribs running crosswise.
If your sluice box doesn't have the bolt-on flair, cover the whole area before the carpet with the matting so the matting butts up against the carpet. The matting holds the fine gold temporarily so you can see it, and it keeps the dirt from gushing, overloading the riffles.
Miner’s moss (entryway matting, scraper mat, backed and “unbackd” by 3M) is preferred over carpeting for trapping fine gold and black sand.
List of panning equipment
- Gold pan(s) (black or green plastic provides best color contrast; not steel pan)
- Small vial(s) (screw-on lid)
- Classifiers (1/8” and 20-30 mesh screen or colanders)
- 5 gallon plastic bucket (to catch concentrate from classifier)
- Bucket (for pouring water--or simply use a gold pan instead)
- Magnet (to confirm and remove black sand hematite)
- Hand lens (to define flakes/dust
- Pin (hat or corsage to confirm gold flake)
- Snuffer (or dry finger works best)