Some Sluice Myths
Before we begin, let’s take a look at all the popular myths surrounding sluice box operations. These same myths are also applicable to the operation of power sluices and dredges. Many of these myths have been discussed at the various prospecting forums for many years and have been presented in various professional papers but still largely go ignored by the vast majority of people who actually use sluices on a daily basis. For this reason we really need to revisit these myths and bring them back to the forefront once again as they are critical elements in the process of how we use and evaluate sluice operations.
The best and most complete list of these myths was originally presented in an 1989 report entitled ‘Gold Losses at Klondike Placer Mines’ prepared for the Klondike Placer Miners Association and we’ll reprint them here.
The first myth is all too common and we’ve all experienced this with our own boxes and that is: “I’ve recovered a lot of extremely fine gold, therefore I’m recovering all of the gold particles which are coarser”.
The truth is that almost any sluice box no matter how primitive will recover a certain amount of fine gold even as larger particles get washed away.
The second myth is also all too familiar and that is: “I’m recovering a lot of small nuggets and flakes so therefore I’m recovering all of the nuggets that are larger”.
Actual test samples at numerous sites have shown that this myth is almost universally false as sluices set up for fine/small gold recovery are very poor at trapping larger particles above 16-mesh in size.
The third myth we’ve all seen or heard mentioned about a thousand times is: “ I’ve panned my tailings and found no gold so my box is getting it all”. Researchers have proven that tailing piles are highly segregated and in their own right very effective concentration devices so to be accurate a person has to pan the bottom of that pile in order to actually sample what the sluice is missing. In other words you really need to re-sluice all of your tailings to actually see how effective your sluice is working and nobody really does this.
This myth is of particular interest because very often reworking tailing piles left by other prospectors can be quite rewarding.
The fourth myth is also one of those classics that has been proven wrong by other researchers even though it still persists and that is: “I recover all of my gold in the first few feet or first few riffles of the sluice so I’m sure that I’m recovering all of the gold in my materials”.
This myth is just plain wrong in almost all respects. Basically if this is what you’re experiencing it means that the lower half of your sluice isn’t working at all and that a lot of gold is just being washed away as it’s pushed back up into the laminar flow strata.
The fifth myth is perhaps the most dangerous and that is when a person falls in love with a particular piece of equipment and won’t give it up even if it doesn’t work. They justify hanging on by some weird twist of logic that goes something like: “This is the most effective gear available and even if I’m loosing some gold it is less than if I used some other gear”.
A good prospector never falls in love with his equipment, as there is no such thing as a ‘perfect’ piece of gear.
The sixth myth is that using riffles of any style in a sluice box will automatically guarantee that you’ll be washing away about 50% of all fine gold that is contained in the source gravels.
Like many other myths this is just not factual in reality. The success or failure to capture fine gold has nothing whatsoever to do with riffles or meshes or capture fabrics but is almost exclusively dependent on proper classification and stratification of source gravels that are run down any type of sluice at a proper velocity.