How to Separate Fine Gold From Black Sand

What black sand is

Black sand is the heavy leftover at the end of panning. The USGS says magnetite is the most common mineral in black sands, “but other heavy minerals such as cassiterite, monazite, ilmenite, chromite, platinum-group metals, and some gem stones may be present.” The BLM and Forest Service booklet for Alaska’s Kenai Peninsula lists magnetite, garnet, scheelite, zircon, cassiterite and platinum.

Black sand is a good sign. The booklet says that when dark, heavy grains are left in the pan, “you are doing the panning right,” and it advises that anything heavy you cannot identify is worth keeping for a geologist or miner to look at.

Tools for black sand cleanup

Step 1: Classify the concentrate

Makers build cleanup around screened material. Keene says to stack its sieves “for fast and effective multi-stage concentration” and to classify material before it goes to a sluice, concentrator or gold pan “to avoid losses caused by unwanted larger materials.” Gold Cube’s machines are built around the same idea and are fed classified concentrates of 1/8 inch. The classifiers and sieves guide has a mesh-to-inch chart for choosing screen sizes.

Step 2: Pan each size group slowly

Work one size group at a time, over a tub. The Kenai booklet says to do final panning “over another container to keep from losing the gold.”

• Use less water. The Washington Division of Geology and Earth Resources says to pour off water until just enough is left “to barely cover the concentrate.”
• Feather it out. Washington says to swirl the pan to “string out” or “feather” the concentrate, so lighter grains wash farther and the gold, “because it is the heaviest,” stays in the tail.
• Rock and swirl. The Kenai booklet describes “a combination swirling and rocking motion” where “lighter material moves to one side, gold stays put.”
• Use a finishing surface. Keene’s SP14 has a textured area “used to pan any remaining black sand” and a smooth surface used “until only the gold remains.” Sluice Fox says its Vanishing Riffle Set is “engineered specifically for finish panning and final separation of fine gold from black sand.” The linked Amazon listing covers all three sizes and colors, so choose the size there: Sluice Fox calls the 9-inch compact for backpacking, the 11-inch mid-size for all-around use and the 15-inch large for processing more material per scoop.

For the motion itself, see how to pan for gold .

Step 3: Dry it and pull the magnetic sand

The Kenai booklet’s finishing steps are to “dry the fines” and “use a magnet to separate magnetic grains.” Its suggested equipment list includes a “small magnet for separating out magnetic black sands.”

• Keene’s A28 Gold Magnet “extracts magnetic sand from gold concentrate and black sand.” You press the button to pick up magnetic sand and release it to let the sand fall free.
• Sluice Fox says its Huntley Sweeper Magnet removes “black sand and other ferrous materials” from concentrates. It comes in 8, 16, 35, 50 and 75 lb strengths, and Sluice Fox says lighter strengths suit “fine cleanup and controlled separation,” while higher ones handle dense concentrates. The linked Amazon listing covers all five strengths, so for finishing fine gold, choose a lighter one there, such as the 8 lb.

Keene markets its larger magnet as removing black sand “with less gold included,” which is a reminder that fine gold can be dragged along with magnetic sand. Look over what the magnet picks up before you throw it out.

Step 4: Collect the gold

The Kenai booklet suggests tweezers, a knife blade or a dry finger for small pieces, and storing the gold “in a water-filled vial.” A snifter bottle is faster for fine gold. Sluice Fox’s 4 oz Snifter Bottle has a 4.75-inch tube with a 3/16-inch diameter; the Amazon link is the single-bottle 1-pack. Garrett’s instructions describe using a bottle “to suck up tiny gold particles, then move them to a gold vial.”

Watch the water surface. The booklet says flour gold “has been flattened to a few microns thickness and will float on water.”

Bigger batches: clean-up sluices and concentrators

The Kenai booklet calls panning “a relatively slow method for recovering gold.” For buckets of concentrate, makers offer machines that cut the volume down first:

• Clean-up sluice. Prospector’s Dream’s FAQ says running concentrates over one of its clean-up sluices “is the fastest way to reduces your cons and make the panning process pretty easy.”
• Concentrating bowl. Keene’s Gold Concentrating Bowl runs on water from a pump, a battery-powered pump or a garden hose, and Keene says it uses 3 gallons of water per minute. Keene’s catalog notes it “requires screening for proper use.”
• Gold Cube. Gold Cube says its machine can take “a large scoop of classified (1/8th) concentrates” and reduce it to “less than a coffee cup,” and claims “90% (or more) gold will be caught in the first tray.” That is the maker’s claim. The sluice box guide covers the 3 Stack Deluxe.

Gold Cube describes the result as “highly concentrated gold and black sand,” so the last step is still a finishing pan and a magnet.

Leave mercury out of it

The USGS says mercury “has a chemical affinity for gold” and forms an amalgam, and that miners used it “to recover gold throughout the western United States.” Among the human-health risks of that mercury, the USGS lists improper handling of contaminated sediments and inhalation of mercury vapors. This guide does not use or recommend mercury. If old concentrates or dredge material contain liquid mercury or amalgam, ask your state environmental agency how to handle it.

Check what you found

A bright speck in black sand is not always gold. Use the gold, pyrite and mica tests before you put anything in the vial.

FAQ

What is black sand in a gold pan?

Heavy mineral grains that settle with gold. The USGS says magnetite is the most common mineral in black sands, and the BLM and Forest Service panning booklet lists garnet, scheelite, zircon, cassiterite and platinum among the others. The booklet says black sand in the pan means you are panning correctly.

Should I use mercury to get gold out of black sand?

No. This guide does not cover mercury. The USGS lists improper handling of contaminated sediments and inhalation of mercury vapors among the human-health risks from historical gold-mining mercury.

Why does my fine gold float?

The BLM and Forest Service booklet says flour gold “has been flattened to a few microns thickness and will float on water.” Pour off water slowly during the final cleanup so floating specks are not lost.

Sources

• BLM and USDA Forest Service, Gold Panning: Guide to Recreational Gold Panning on the Kenai Peninsula (2018 revision) (black sand minerals, finishing steps, magnet, vials, flour gold)
• U.S. Geological Survey, Gold (General Interest Publication) (minerals in black sands, mercury and amalgam)
• U.S. Geological Survey, Mercury Contamination from Historical Gold Mining in California (Fact Sheet 2005-3014) (historical mercury use, health risks)
• Washington Division of Geology and Earth Resources, Recreational Gold Panning (feathering the concentrate)
• Keene Engineering, 2022 catalog (classifying sieves, concentrating bowl screening)
• Keene Engineering, 14 Inch Super 3-Stage Gold Pan (pan surfaces, size)
• Keene Engineering, Gold Magnet (A28) (magnetic sand removal, button release)
• Keene Engineering, The Big Orange Gold Magnet (A28A) (less gold included)
• Keene Engineering, Gold Concentrating Bowl (GCB) (water sources, water use)
• Sluice Fox, Handheld Black Sand Magnet (Huntley Sweeper) (uses, strengths)
• Sluice Fox, 4 oz Snifter Bottle (capacity, tube size)
• Sluice Fox, Spiral Gold Pan with Vanishing Riffle (finishing design, sizes)
• Garrett, Gold Pan Kit 1651310 (bottle use)
• Gold Cube, How it works (classified concentrates, first-tray claim)
• Gold Cube, 3 Stack Deluxe (12-volt pump)
• Prospector’s Dream, FAQ (clean-up sluices for concentrates)