Nuggets of News Blog 

If you’re used to water mining, having success in the desert might seem challenging— that is until you start thinking of desert ground as a massive sluice box. Many of the principles you’re used to when prospecting and mining in waterways, will translate into desert mining. The most important thing to remember is that water is crucial to gold movement. Unlike a running river or creek with highs and lows, desert placers are much different in that gold is moved quickly during a flash flood, leaving gold stranded as opposed to being moved further by continual water flow in a creek.

During a river high-water event in a non-arid area, gold is moved over a larger area by massive water flows that continue until the water slows as the source dissipates its energy. Spring snow runoff is a good example. Rivers rise and sometimes flood based on the upstream water source. When the snow has melted, the river will slowly get back to  normal. In the desert, gold is moved in the exact same way with the exception that water powerful enough to move gold does so and then just simply stops. In a flash flood, gold is moved very violently and often a very short distance, sometimes percolating into valuable pockets. Here’s where the difference between water and desert mining principles comes into play generally flood gold will concentrate in areas that do not meet the standard thought of inside bends and where the water flow becomes lower.

For the most part, desert mining experts recommend staying out of the washes, gulches and dry river beds— that is unless you clearly see exposed bedrock. Gold will settle fairly quickly when it is trapped behind jagged bedrock and small fault lifts that have not been worn down over time by constant water flow. It IS true you can find areas of concentrated gold-bearing material in the washes, however, the amount of time and energy to get through feet of overburden is usually just not worth it, especially when there are higher values to be found outside of the wash.

Follow the leads out of the wash to where the gold lives in higher concentration. Test and sample areas you see with a great deal of runoff from a tributary coming into the main wash. Here you are only digging through the current flood layer and testing for flood gold. Make your way out of the wash carefully looking at the bottom of the tributary and the areas where the water flowed into the tributary. Look closely for jagged bedrock and slight lifts in the ground and then prospect. Continue to test each of those spots. What started as a few specks of flood gold in the main wash can lead to larger and larger deposits on the flats or in slight inclines across the desert floor. Keep in mind that when a flash flood is dissipating, there is not enough energy to move a lot of rock, but the sand will continue to flow a bit, creating great clues.

In general, cool season precipitation (October through April) is the most extensive source of rain in the desert regions. Rainfall is more widespread and of relatively long duration during the cool season. On the other hand, warm season precipitation (May through September) results largely from short monsoon-type thunderstorms.

If you’re ready to head to a sunnier climate this winter, keep these tips in mind and you just might find enough similarities between water and desert mining to make you return every year.  Good luck!

Gold is gold, so there isn’t necessarily a better type of gold, however, mining for lode gold has many more challenges than mining for  placer gold. The formation of gold generally starts as a vein in rock. This is referred to as “lode gold” and is formed when molten rock in the earth’s crust heats groundwater under great pressure. In fractured bedrock with appropriate rock chemistry, super-heated water (hydrothermal) at approximately 400-700 degrees Fahrenheit dissolves certain elements and molecules from cubic miles of crust and transports them in a circulation loop. When this hydrothermal solution cools or chemically reacts with local rocks, the elements and molecules will come out of the solution and solidify (precipitate), forming ore deposits. The hydrothermal solution will begin precipitating on the sides of the opening and slowly fill the entire crack over time. This is how gold veins can form.  These geologic processes take place over millions of years, and can happen many times over many years in the same location.  Since the gold is locked up in rock, it is usually pretty hard to get to— usually requiring specialized mining techniques to mine and extract. Lode mining takes a lot more equipment and generally a lot more expense and is usually undertaken by large commercial operations instead of the average prospector.

Placer gold is the gold that most prospectors are more familiar with.  Placer gold isn’t really any different than lode gold. It is simply a concentration of gold that is created over time as it erodes from hard rock veins.  When exposed at the surface, a mineralized deposit will break down and erode due to reactions with oxygen, water and wind, coupled with temperature fluctuations. Since gold is very dense, it will move downhill much slower than the surrounding sediment. It tends to become concentrated on or near the surface of the lode, forming a “residual placer” close to the original bedrock exposure. Gold found downhill from the immediate outcrop above the nearest watercourse is called an “eluvial placer.” Once it reaches the nearest waterway and is transported by flowing water, the gold now forms an “alluvial placer.”  The origin of the dust, flakes and nuggets found by panning and sluicing is usually from a vein up on a nearby mountain.

An ore body is a mineral deposit that can be mined, processed and sold at a profit. All ore bodies are deposits. Few deposits are actual ore bodies. Valuable gold deposits in placers are referred to as “pay streaks” instead of ore bodies. Over time, eluvial and alluvial placers can become covered with sediment. When buried long enough and deep enough, these deposits will turn into “fossil placers.”  Sometimes the fossil placers are re-cemented into sandstone or conglomerate rock and then must be mined using hard rock techniques.

Hard rock ores have mostly fine to micro-fine gold in solid rock; placers contain fine to coarse gold particles in a softer bulk material or matrix. That makes placers much easier to mine and process. Moving soft soil or river gravel is obviously much easier than breaking rock. For small scale miners, though, a rock crusher can pulverize 2 or 3 inch sized rocks into powder in no time!  But for the average prospector, panning and sluicing will be more fun and more profitable, and as time goes on, you may wish to upgrade your mining efforts with a highbanker or power sluice, dredge or trommel. Good luck!

If you’re ready to head to a sunnier climate this winter to do some desert prospecting, understanding the weather and topography can add to your success. Before loading up and heading to the Southwest, only to be disappointed by bad weather, first check out the weather patterns for the last 60 days and the predicted weather for the next 30-60 days. Why is that important?  Well, it mostly comes down to rainfall— how much and how fast. For example, if there will be a lot of rainfall over an extended time, soils will be loosened and gravity will do its job and cause deeper, and sometimes more concentrated, pay streaks. In general, cool season precipitation (October through April) is the most extensive source of rain in the desert regions. Rainfall is more widespread and of relatively long duration during the cool season. On the other hand, warm season precipitation (May through September) results largely from convective precipitation in the form of short monsoon-type thunderstorms. 

There are three major desert areas that make up the American Southwest:

The roughly 200,000-square-mile Chihuahuan Desert stretches from the southeastern corner of Arizona across southern New Mexico and west Texas to the Edwards Plateau. It runs deep into central Mexico,The Chihuahuan Desert is the most moderate of the three deserts, made up of low and high desert regions and grasslands. It sees the most rain on a regular basis throughout the year with anywhere between 8-12 inches, and areas in New Mexico receive up to 17 inches per year. Unfortunately, because of the Chihuahuan Desert’s higher altitude in southern New Mexico, and the rain patterns there, winter prospecting is a real challenge, especially dry washing. October - March averages 2 inches of rainfall per month, with an average daytime temperature of 55 degrees, making it hard for the ground to dry throughout the season. The pay layer in the Chihuahuan Desert is most likely going to be deeper and more evenly distributed and more highly concentrated than in the Sonoran Desert, but there will be a lot of effort needed to stay on track sampling to find the richest pay layer.

The Sonoran Desert occurs primarily in Mexico. In the USA, most of it can be found in the southern third of Arizona, with small areas in southeastern California.The Sonoran Desert region of Arizona receives between 3-20 inches per year, but these numbers are skewed for the actual low desert gold-bearing region of the state. The Sonoran Desert encompasses a large section of high desert area, ending a few miles south of Prescott, Arizona, following a higher elevation line to the east and west. The normal rainfall in the lower elevation gold-bearing areas of Arizona averages 6 inches annually, all of which falls in about 30 days and includes the monsoons. Yuma is considered the driest area of the state with only 3 inches of rain on average.

The Mojave Desert is primarily in southeastern California and southwestern Nevada, with small portions extending into Arizona and Utah. It has a large amount of high desert elevations and has skewed numbers for the majority of the gold-bearing areas. Lowland areas at less than 1,000 feet elevation average 3.7 inches per year of rain, while Granite Mountain at 4,200 feet above sea level averages 8.5 inches annually. Rich pay layers have been found northwest of Barstow, California by testing and eliminating low to no pay overburden. This area is known for seismic activity with several earthquakes and aftershocks occurring west of the 117 degree meridian, which helps in concentrating gold.


When prospecting in the desert, it’s a good idea to test larger areas in compass headings— testing every few feet north to south to find highest values, then east to west of that spot. Doing so provides you with a line in the desert for further testing. Because of the extended days of rainfall in the Chihuahuan and most of the Mojave compared to the Sonoran Desert, you’ll likely discover a shallow and slightly more compacted layer of good material that is worth processing. However, this “pocket gold” layer can be directly above the really good pay layer you want. Finding gold and digging straight down without continued testing and sampling is not taking advantage of the forces of nature, especially that of water following the path of least resistance and taking the heavies along for the ride. In other words, don’t settle for just any pay layer— follow and use the over burden to get to the BEST pay layer!

If you are planning a desert prospecting trip far in advance, it’s a good idea to start checking weather patterns in April, which is when desert prospecting begins to wind down. That way you will be very prepared when the following fall and winter rolls around. That also gives you time to form a Plan B if the weather is not conducive to your Plan A. If you are a member of Gold Prospectors Association of America (GPAA), there are hundreds of opportunities across the Southwestern states to get on the gold at a GPAA claim. Knowing a little about desert geology is a great start to understanding more about the “why” and “how” gold deposits are formed. And weather is a key factor in knowing “where” gold settles after it breaks from the lode and residuals. Get out there and get your share! Good luck getting the GOLD!

When prospecting an area that’s known for gold, put yourself in the boots of the old-timers who came before to help you decide where to begin. Look at your site from all directions and think about what they could and could not do way back then. Your modern-day equipment and knowledge are a lot more advanced than what they had to work with, so you’re already a step ahead! Many times miners jumped in with both feet and started mining to beat the other guys. But being in a hurry meant they could have missed a lot, or moved on too quickly from their original discovery before it was completely worked out. Considering the lay of the land will reveal important clues that can help you better formulate a plan when you're out in the field. Here’s what to look for:

Host rock (or bedrock) could be shale, diorite, granite, quartz, clay or other material. Keep an eye out for changes in the area’s host rock and notice the direction in which it’s running.

Contact zones occur when a rock or mineral cuts or crosses the host rock. Generally, gold is deposited along contact zones, which can be a few inches or several hundred feet wide. If bedrock in your area runs north to south and you notice a color change in material that runs east to west, you’ve found a contact zone.

Outcroppings are a lump of high ground with weather-worn rocks which are generally rounded and usually situated on ridges, but can be located anywhere. Especially look for iron staining on outcroppings.

Ditch lines of yesteryear were generally dug into and run along somewhat level ground. Very close to diggings, especially in hilly or steep terrain, they may have been cut loose to wash downhill.  Follow the old water ditches and see where they end up.

Exploratory trenches were not used for water but most of the time were deeper and would often circumnavigate a rich area that may be throwing gold from clay lines, pockets, quartz seams and any other local contacts. Trenches were dug simply to expose any contacts that may be present. As a contact was crossed, old-timers checked it out in both directions for values.

Rock cairns are piles of rock or stone used for claim corners. Standing high on a slope looking down is a great vantage point from which to spot cairns and other man-made landmarks. By locating a historic claim, you definitely have a great place to begin! 

A good rule of thumb that most prospectors agree on is to look for placer gold on bedrock and within crevices in the bedrock. This simple principle makes sense— placer gold is heavy and dense and therefore settles at the lowest point as it is pushed around by flowing water. However, gold isn’t always going to make it all the way down to true solid bedrock at the bottom of all gravels. Instead, in certain conditions, it will be found ABOVE bedrock. When these conditions exist, gold will collect on “false bedrock.” For example, a clay layer in streams can act like bedrock and yield more gold than the true bedrock below it. 

Another situation where gold cannot make it to bedrock is where the streams and gullies have “caliche.” Caliche is a form of cemented gravel often found in desert areas. The gravel is deposited by water flows, just as it would be in any other stream. The difference is that the water contains dissolved calcium salts, and as the water dries up in the streambed, the calcium salts turn into calcium carbonate or calcite. This material gets deposited on the gravel a little at a time and eventually the calcite glues it all together into a solid mass. The solid mass then acts like false bedrock and any new gold flowing across it is stopped in its downward movement by the caliche.

Residual placer gold is formed near the source of the gold and doesn’t really have a chance to work its way downward. Hillside placers are residual placers that are sliding and making their way down the side of a hill into a stream drainage. Gold generally is distributed all through these types of gravels and is not concentrated in any one place. A hillside placer often will be located up above a stream, making it difficult to determine it from a bench placer. Old benches of river gravel can be good places to prospect because they are virgin ground, but because the river used to flow at this location, it’s highly likely that the best gold will be right on bedrock or in crevices of the bedrock. The best way to tell the difference between hillside and bench placers is the shape of the rocks in the gravel. If the gravels and rocks are well-rounded and smoothed, then it’s probably an old river bench. If the gravel is angular, pointy, and sharp, it’s probably a hillside placer that hasn’t yet made its way into a stream.

Another type of placer—the windblown placer— concentrates on the surface, just exactly the opposite of what you would find in a river or stream. The lightest materials such as sand and silt are blown away by the wind. Heavy materials like gold remain behind on the surface. These types of placers are marked by desert pavement, which is a concentration of small to medium-sized rocks that cover the surface and prevent continuing wind erosion. They occur in dry regions with flat terrain, and are often favorite locations of metal detectorists who find nice nuggets at shallow depths.

The next time you find yourself in an environment with well-washed river gravels, you know that the gold will most likely be on the bedrock. But if you find yourself in other types of environments, especially in the desert, consider the possibility that the best gold may actually collect ABOVE it.  Good luck!