Prospecting Equipment 4

deep hole

Trommels or Spiral Sluice

Recirculating Trommel
Ed Ramos’s recirculating trommel.

Trommels are made in a wide variety of sizes, from small recreational units to very large ones for commercial mining operations and other commercial uses. They also can be made into recirculating units for use in areas with little or no water. Some varieties act mainly as a classifier with the revolving action being used to break up clay and separate any gold that might be caught in organic material or stuck to other rocks. Others combine this with a spiral sluice to also separate the heavier concentrates from the lighter materials. A couple of members own trommels, both bought from Columbia Mining & Equipment, 18169 Main, Jamestown, CA 95327, ph. 209-984-3893 at gold shows in Arizona, one of which is pictured here. They seem to work well and you can see the results quickly as concentrates are discharged at the top, usually into a bucket. These concentrates can be examined for gold at any time.

As sold by Camel Mining Products, a spiral sluice seems to operate on a similar principle to a Gold Wheel. One is made by “Gold Screw” and called a Revolving Spiral Sluice. It is shaped like a cylinder and revolves around the cylindrical axis. The following description is from their web site. “The Gold Screw will accept material up to tennis ball size. This material is received by a revolving trommel which classifies the material and allows the gold and heavier concentrates to drop into 60 ft. of spiral riffles. Reverse screw action carries the concentrates upward. A regulated flow of water from the pump further concentrates the material before being deposited into the flume. If gold is in the material being processed, it will clearly be seen at the head of the flume in less than a minute. This gas powered trommel is compact and weighs only 175 pounds.”

How Trommels Work. Plans and pictures for building a Mini Trommel can be found at Bill and Linda’s Prospecting page.

Spiral or Gold Wheel or Spiral Panner

Carter's Gold Wheel
Carter Thoenes putting his concentrates into his gold wheel.
Gary's Gold Wheel
Gary Grant running his concentrates through his gold wheel.

Designed for cleanup work, not as a primary prospecting tool. Used to separate gold from the black sand concentrates. If there is a lot of black sand, it is very time consuming to separate out the gold by panning. This method separates out most of the black sand though some panning may still be required. These are especially useful when dealing with large quantities of concentrates produced by other methods.

These come in a variety of sizes, from 13 to 18 inches. All are round with spiral ridges, hence the name, and like gold pans are made in a variety of colors. Most use a 12 volt DC power source while others are manually operated, although they can usually be converted to 12 volts. Many are designed to recirculate water and even have a self-contained carrying case. Some units have built in agitators for a vibrating action. Several manufacturers claim that their units will work wet or dry, although wet methods are more efficient.

Metal Detectors

Falcon gold probe
Jack Stephenson playing with his Falcon gold probe.
George metal detecting
George Volker doing a little metal detecting.
Club nugget shoot
If you want to see lots of detectors, attend one of our nugget shoots.

The all around device, as these are not dependent on a source of water and are usually lightweight. However this requires a lot more patience in the beginning as you can go a long time without finding gold before you get good at it, while with most other methods one can find at least a little gold right away. One club member found his first gold nugget after 5 years of hunting. As a matter of fact, he found 3 nuggets so it pays to be presistent. They can be used strictly for nugget hunting or can also be used to check your oversize tailings while placering with other methods to be sure that larger nuggets have not been discarded.

Metal detectors can be classified into two broad categories. Most use a continuous frequency, such as BFO and Induction Balance (VLF, TR) types, while some use a series of pulses (Pulse Induction), each has their niche. Many detectors can be fitted with a wide assortment of replaceable coils except for the units referred to as “Gold Probes” which have the coil built into the unit.

The most popular units among club members are the White’s Goldmaster series, followed by equal amounts of Fisher Goldbugs, Minelabs and the Tesoro Lobo. Even though there are strong opinions regarding these detectors, nuggets have been found by club members using all of these units. Selection is a personal choice.

BELDA’S metal detectors sales has a page on “detecting tips and techniques” for proper use of a metal detector. Essex Metal Detectors, a British manufacturer, has a page on building your own metal detector, a simple cheap BFO and another page on metal detector patents. A BFO is not as sensitive as modern detectors but can be handy for mineral differentiation. Kellyco Metal Detectors has been around for many years and offers a large selection of metal detectors and accessories.

How Metal Detectors Work by Jeff Tyson is a good introduction to the types of metal detectors and how they work. For those interested in learning more about how metal detectors work, Links for land mine detection has many interesting links to metal detecting theory, especially under the “Metal Detection” section in the “Theory” and “Circuits” categories. Two good examples are A comprehensive analysis and survey of all metal locator techniques and principles by Cris G Martin and either How Metal Detectors Work or How Metal Detectors Work by Mark Rowan & William Lahr. A

For anyone interested in learning more about the inner workings of a metal detector, the original patents can be viewed online at the web site of the United States Patent and Trademark Office. The main search page at Searches for USPTO website shows many of the searchable databases. The Patent database at Databases: Patent Grant and Patent Application Full-Text and Full-Page Images can be searched for metal detector patents. For older patents, you can do a search at Delphion intellectual property network – International and US patent search database and use the patent number you find to access the patent in the USPTO patent database.

Ore carts on track divider

Notes on graphics:

All clip art on this page created by Jamie Girard and donated to the Tucson Desert Gold Diggers. Copyright © 2002 by the Desert Gold Diggers.