Gold Deposit
Snake River Gold
By…Lawrence L. Dee, Geologist
Introduction
The Snake River begins at the continental divide in the Teton Range of Western Wyoming. Flowing southward, it follows an arc across southern Idaho until it eventually heads north and forms the western border of the state, and finally joins the Columbia River in south central Washington. Gold has been found throughout most of the 800-mile length of the Snake River from the headwaters near Yellowstone National Park to Lewiston, Idaho.
The source of the Snake River gold was the subject of considerable speculation around the turn of the century. Some researchers felt that the gold was supplied by streams entering the Snake and by lavas lying close to the river. Many theories were advanced to explain how such a large river could have the huge number of fine gold deposits that were being found.
We now recognize that the gold was derived from the deposits in the Rocky Mountains near Yellowstone National Park and that it originated as fine particles. An interesting fact concerning Snake River gold is that the Green River of Utah contains similar fine gold, also derived from the same source.
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Snake River Gold
Snake River gold is unlike most of the gold that was mined during the gold rush days in Idaho. It is found in very fine particles called “flour” or “float” gold. There are good reasons for these names. While not as fine as flour, they probably seemed like it to the hard working miner. The particles do float if contaminated with oil or if the recovery water is too turbulent. This was one of the many problems faced by the miner attempting to recover the Snake River gold from the sand and gravel. The main consideration was and still is today, that the gold is so fine and light that the particles have little value.
Thus it took a tremendous amount of work to obtain enough gold from the gravels to return a profit. It is estimated that at least 1000 colors or particles were necessary to equal one cent in value using the old gold value of $20 per ounce. At a gold value of $300 per ounce, 67 colors would be needed to equal one cent.
Millions of dollars in gold remain in the Snake River sands and gravels. Modern prospectors and miners still attempt to recover the bright colors that, unlike most placer gold, are almost pure. So far no one has shown that it can be done at a profit except for a handful of gravel operators with processing plants along the river. They are able to sell the tremendous amounts of gravel that must be mined in order to produce enough gold to realize a profit.
Mining History
The earliest recorded mining on the river was by soldiers from Fort Boise who mined near where the Boise River joins the Snake. Rich gold discoveries in the Boise Basin in 1863 encouraged two thousand miners to rush to the upper Snake River believing there was gold in abundance. The newspapers later reported their disappointment when they could either not find gold or it was so fine that they could not recover it. Later in the century, the burlap sluice was devised and then it became feasible to mine some of the better deposits along the river.
By the 1870s, most of the miners on the river were Chinese. As was generally the case in western placer camps, the Chinese were relegated to the low grade deposits which the Snake generally contained. The deposits said to provide the best returns on the entire river were located on Bonanza Bar west of American Falls. This site, as well as the area from Raft River to Buhl, was extensively worked during the late 1800s and into the 1900s. Many old mining sites were reopened during the Depression when a man could make two or three dollars a day working the gold bearing gravels and enjoy himself while doing it.
Several sizeable mining camps sprang up along the Snake during the late 1800s. Dry Town, near the present town of Murtaugh, had four stores, a restaurant, and about six residential tents. A local newspaper stated that “Shoshone City, the largest hamlet on the river, consists of four canvas shanties, and a tent, all used as trading posts.” A town called Springtown was built on the north and south sides of the river near the Hansen Bridge, and a camp called Mudbarville existed near Buhl.
Gold Dredges On the Snake
Several large dredges were built and operated on the Snake in attempts to economically recover the fine gold. The first, the Burroughs Dredge, was reportedly built about 1892 and operated from the mouth of the Raft River down to the Starrhs Ferry Ganyon. The dredge consisted of a boiler, engine, and six-inch sand pump. The richest gravel it found was at the mouth of the Raft River which ran 37 cents a cubic yard (gold at $20/ounce). The Burroughs dredge was very modern for its time and was capable of washing about 200 cubic yards of gravel per day. However, it suffered greatly from downtime because of the large boulders that were caught up in its suction pipe.
The second dredge was built by the Sweetser-Burroughs Mining Company and operated in the river in the area from where the Raft River joins the Snake to near Burley. This suction-type dredge operated for about ten years and, because of its low operating costs, did return profits. The mining company also built large water wheels in the river just below the present site of Minidoka Dam, and raised water for sluicing the sand on 216 acres of mining claims. This did not prove very successful and the wheels were later used for irrigation.
Gold Deposits
Early mining and geological reports on Snake River gold mining indicate that some deposits produced thousands of ounces of gold but were generally exhausted within a year or two. In 1890, one writer stated that a mining claim could be opened for about $5000 and return from $10-$50 per day (gold at $20/ounce); it was stated that $5000-$10,000 in gold could be recovered from an acre of ground by special blanket sluices designed to save the fine gold. The writer did not say how many men would be needed for the returns, but he stated it must have been a large crew.
As in most placer mining districts, the deposits that were easiest to work and most productive were quickly claimed and worked out. In later years, as well as today, what remained were bar and bedded gravel deposits containing very fine gold in quantities which today probably do not exceed $5 per cubic yard at the very most. The values reported by credible miners and prospectors today range from a few cents to a high average of $3 per cubic yard.
In the early days of Snake River mining, the gold was recovered by use of a device called a “burlap table.” Recovery was reported to be 90 percent or more if properly operated. It would be difficult to utilize this labor intensive device today unless gold prices were to rise considerably. The era of Snake River gold mining remains an exciting part of Idaho’s history. The Snake River deposits are certainly one of the most interesting and unique gold deposits in North America.
Distribution of the Gold
Snake River gold is generally distributed throughout the length of the river and can be panned just about anywhere. The gold deposits occur wherever sediments are present in the river itself, adjacent to the river, and above the river. The early miners apparently found large deposits of the fine gold in the river, called river bar deposits. They also discovered gold above the river in deposits known as “skim bars” and “bench gravels.”
The large bar deposits in the river were worked by the early dredges – some quite successfully. The small to medium sized mining operations on land worked the skim bar and bench deposits. The skim bar was an ancient river bar in which the gold was concentrated in the top few inches or feet of sand and gravel. These were usually worked by one or two men using rockers. Bench gravels were elevated bars in which the gold was concentrated in “paystreaks” at the surface or somewhere in between the surface and bedrock. These paystreaks varied in thickness from a few inches to several feet and could occur almost anywhere within the deposit. An unusual mining situation existed at Drytown, near the present town of Murtaugh, where the gold was mined by digging the sand and gravel from between huge boulders deposited by the Bonneville Flood.
Unlike most coarse gold placers where the weight of the gold particles allows them to settle on or near bedrock, the Snake River flour gold is not concentrated on or close to bedrock. The reason for its erratic distribution is that the gold particles are so light that the action of the water moves them along rather than allowing them to concentrate at every point where the current slows as it would in a coarse gold deposit. The concentration of Snake River gold was largely based on the speed of the river current at the time the gold was deposited. Thus the term “flood gold” refers to fine gold deposited during spring floods.
Often the deposit was covered with barren sand and gravel which could be tens of feet thick. This was removed by hydraulicing or ground sluicing until the paystreak was reached. The paystreak was then mined by washing the gravel through the special burlap sluices used to recover the gold.
Home » Gold » Gold Prospecting in the United States
Gold Deposits Map
Republished from 'Prospecting for Gold in the United States,'
a general interest publication of the US Geological Survey by Harold Kirkemo.
Lode gold: Gold ore from the Olinghouse epithermal deposit. When gold is found in the rocks where it crystallized, it is known as a 'lode deposit.' USGS image.
The Many Rewards of Finding Gold
Anyone who pans for gold hopes to be rewarded by the glitter of colors in the fine material collected in the bottom of the pan. Although the exercise and outdoor activity experienced in prospecting are rewarding, there are few thrills comparable to finding gold. Even an assay report showing an appreciable content of gold in a sample obtained from a lode deposit is exciting. The would-be prospector hoping for financial gain, however, should carefully consider all the pertinent facts before deciding on a prospecting venture.
Few Prospectors Find Valuable Gold Deposits
Only a few prospectors among the many thousands who searched the western part of the United States ever found a valuable deposit. Most of the gold mining districts in the West were located by pioneers, many of whom were experienced gold miners from the southern Appalachian region, but even in colonial times only a small proportion of the gold seekers were successful.
Hydrogeochemical prospecting for gold: Groundwater collected from wells, springs, and drill holes may provide clues to the presence of subsurface gold deposits. As groundwater flows through the deposit, minute amounts of gold are leached from the rocks. These can sometimes be detected in groundwater samples collected from wells located down gradient from the deposit. USGS image.
The US Has Been Heavily Prospected
Over the past several centuries the country has been thoroughly searched by prospectors. During the depression of the 1930's, prospectors searched the better known gold-producing areas throughout the Nation, especially in the West, and the little-known areas as well. The results of their activities have never been fully documented, but incomplete records indicate that an extremely small percentage of the total number of active prospectors supported themselves by gold mining. Of the few significant discoveries reported, nearly all were made by prospectors of long experience who were familiar with the regions in which they were working.
Gold Panning made easy: Gary Smith, a gold panner from British Colombia with 40 years of experience, demonstrates his panning methods and gives advice. More gold panning videos.
Prospect Where Gold Has Been Found Before
The lack of outstanding success in spite of the great increase in prospecting during the depression in the 1930's confirms the opinion of those most familiar with the occurrence of gold and the development of gold mining districts that the best chances of success lie in systematic studies of known productive areas rather than in efforts to discover gold in hitherto unproductive areas.
The development of new, highly sensitive, and relatively inexpensive methods of detecting gold, however, has greatly increased the possibility of discovering gold deposits which are too low grade to have been recognized earlier by the prospector using only a gold pan. These may be large enough to be exploited by modern mining and metallurgical techniques. The Carlin mine near Carlin, Nevada, produced gold from a large low-grade deposit that was opened in 1965 after intensive scientific and technical work had been completed. Similar investigations have led to the discovery of a Carlin-type gold deposit in Jerritt Canyon, Nevada.
Gold Panning made easy: Gary Smith, a gold panner from British Colombia with 40 years of experience, demonstrates his panning methods and gives advice. More gold panning videos.
Gold dredge: A floating gold dredge operating near Fairplay, Colorado in 1950. Machines like this could dredge up hundreds of tons of sediment per day and process it to remove the gold. USGS image.
Many Placer Deposits Have Been Worked - Twice
Many believe that it is possible to make wages or better by panning gold in the streams of the West, particularly in regions where placer mining formerly flourished. However, most placer deposits have been thoroughly reworked at least twice--first by Chinese laborers, who arrived soon after the initial boom periods and recovered gold from the lower grade deposits and tailings left by the first miners, and later by itinerant miners during the 1930's.
Geologists and engineers who systematically investigate remote parts of the country find small placer diggings and old prospect pits whose number and wide distribution imply few, if any, recognizable surface indications of metal-bearing deposits were overlooked by the earlier miners and prospectors.
Convergent plate boundaries are the plate tectonic setting of many gold deposits. There, magma produced by the melting of descending lithosphere rises as magma chambers and crystallizes close to the surface. Gold in these hot environments is often dissolved in superheated water and carried away from the magma chamber along faults and fractures. The water temperature is very high near the magma chamber but drops with distance. As the water travels farther from the magma chamber, gold starts to crystallize out within the fracture to produce a vein gold deposit. USGS image.
Financial Challenges of Gold Prospecting
One who contemplates prospecting for gold should realize that a successful venture does not necessarily mean large profits even if the discovery is developed into a producing mine. Although the price of gold has increased significantly since 1967 when the fixed price of $35 an ounce was terminated, the increases in the cost of virtually every supply and service item needed in prospecting and mining ventures have kept profit margins at moderate levels, particularly for the small mine operator. In general, wide fluctuations in the price of gold are not uncommon, whereas inflationary pressures are more persistent. The producer of gold, therefore, faces uncertain economic problems and should be aware of their effects on his operation.
Convergent boundary map: A present-day convergent boundary is located along the Pacific Northwest portion of the United States and extends north along the coast of Canada. Volcanic activity there will produce the gold deposits of the future. Gold deposits being mined today were produced by ancient activity on current plate boundaries or ancient activity on boundaries that are no longer active. USGS image.
Knowledge of Laws and Property Ownership
Today's prospector must determine where prospecting is permitted and be aware of the regulations under which he is allowed to search for gold and other metals. Permission to enter upon privately owned land must be obtained from the land owner. Determination of land ownership and location and contact with the owner can be a time-consuming chore but one which has to be done before prospecting can begin.
Determination of the location and extent of public lands open to mineral entry for prospecting and mining purposes also is a time consuming but necessary requirement. National parks, for example, are closed to prospecting. Certain lands under the jurisdiction of the Forest Service and the Bureau of Land Management may be entered for prospecting, but sets of rules and regulations govern entry. The following statement from a pamphlet issued in 1978 by the U.S. Department of the Interior and entitled 'Staking a mining claim on Federal Lands' responds to the question 'Where May I Prospect?'
'There are still areas where you may prospect, and if a discovery of a valuable, locatable mineral is made, you may stake a claim. These areas are mainly in Alaska, Arizona, Arkansas, California, Colorado, Florida, Idaho, Louisiana, Mississippi, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming. Such areas are mainly unreserved, unappropriated Federal public lands administered by the Bureau of Land Management (BLM) of the U.S. Department of the Interior and in national forests administered by the Forest Service of the U.S. Department of Agriculture. Public land records in the proper BLM State Office will show you which lands are closed to mineral entry under the mining laws. These offices keep up-to-date land status plats that are available to the public for inspection. BLM is publishing a series of surface and mineral ownership maps that depict the general ownership pattern of public lands. These maps may be purchased at most BLM Offices. For a specific tract of land, it is advisable to check the official land records at the proper BLM State Office.'
Core drilling for gold: Core drilling the Bend massive sulfide deposit, located in the Medford District of the Chequamegon National Forest, Michigan. It is a small, metal-rich sulfide body hosted by Early Proterozoic Penokean volcanics. The mineralized horizon subcrops beneath 100-120 feet of glacial cover, and consists of massive pyrite with varying amounts of chalcopyrite, tetrahedrite-tenantite, bornite, arsenopyrite, chalcocite, and rare gold-silver tellurides. USGS image.
Small Prospectors and Total Gold Production
Successful gold mining under present conditions is a large-scale operation, utilizing costly and sophisticated machinery capable of handling many tons of low-grade ore each day. The grizzled prospector with a burro is no longer a significant participant in the search for mineral deposits, and the small producer accounts for only a minor share of the total production of metals including gold.
Gold core at the lab: The core recovered from the Bend massive sulfide deposit (see drilling photo above) was 3' in diameter and was recovered in 10-foot sections. The sections were extracted from the drill stem into plastic bags and taken to a laboratory for careful examination, sampling and analysis. USGS image.
Study, Persistence and Financial Backing
Some degree of success in finding gold still remains for those choosing favorable areas after a careful study of mining records and the geology of the mining districts. Serious prospecting should not be attempted by anyone without sufficient capital to support a long and possibly discouraging campaign of preliminary work. The prospective gold seeker must have ample funds to travel to and from the region he selects to prospect and to support the venture. He must be prepared to undergo physical hardships, possess a car capable of traveling the roughest and steepest roads, and not be discouraged by repeated disappointments. Even if a discovery of value is not found, the venture will have been interesting and challenging.
Fortitude Mine in Nevada produced about 2 million ounces of gold between 1984 and 1993. USGS image.
Public Information for Gold Prospectors
Locations of important gold-producing districts of the United States are shown in some of the reports of the United States Geological Survey listed at the bottom of this page. Geological surveys of the principal gold-producing States where additional information may be obtained also are listed. Information may be obtained, too, from U.S. Bureau of Mines State Liaison offices located in the capital cities of most States. There are also a large number of layman's books about gold that describe gold deposits and gold prospecting.
Hydraulic placer mining at Lost Chicken Hill Mine, near Chicken, Alaska. The firehose blasts the sediment outcrop, washing away sand, clay, gravel and gold particles. The material is then processed to remove the gold. USGS image.
The Geology of Placer Deposits
A placer deposit is a concentration of a natural material that has accumulated in unconsolidated sediments of a stream bed, beach, or residual deposit. Gold derived by weathering or other process from lode deposits is likely to accumulate in placer deposits because of its weight and resistance to corrosion. In addition, its characteristically sun-yellow color makes it easily and quickly recognizable even in very small quantities. The gold pan or miner's pan is a shallow sheet-iron vessel with sloping sides and flat bottom used to wash gold-bearing gravel or other material containing heavy minerals. The process of washing material in a pan, referred to as 'panning,' is the simplest and most commonly used and least expensive method for a prospector to separate gold from the silt, sand, and gravel of the stream deposits. It is a tedious, back-breaking job and only with practice does one become proficient in the operation.
California Placer Deposits
Many placer districts in California have been mined on a large scale as recently as the mid-1950's. Streams draining the rich Mother Lode region--the Feather, Mokelumne, American, Cosumnes, Calaveras, and Yuba Rivers--and the Trinity River in northern California have concentrated considerable quantities of gold in gravels. In addition, placers associated with gravels that are stream remnants from an older erosion cycle occur in the same general area.
Gold Deposits By Country
Alaska Placer Deposits
Much of the gold produced in Alaska was mined from placers. These deposits are widespread, occurring along many of the major rivers and their tributaries. Some ocean beach sands also have been productive. The principal placer-mining region has been the Yukon River basin which crosses central Alaska. Dredging operations in the Fairbanks district have been the most productive in the State. Beach deposits in the Nome district in the south-central part of the Seward Peninsula rank second among productive placer deposits of Alaska. Other highly productive placers have been found in the drainage basin of the Copper River and of the Kuskokwim River.
Montana Placer Deposits
In Montana, the principal placer-mining districts are in the southwestern part of the State. The most productive placer deposit in the State was at Alder Gulch near Virginia City in Madison County. Other important placer localities are on the Missouri River in the Helena mining district. The famous Last Chance Gulch is the site of the city of Helena. There are many districts farther south on the headwaters and tributaries of the Missouri River, especially in Madison County which ranks third in total gold production in the State. Gold has been produced at many places on the headwaters of the Clark Fork of the Columbia River, particularly in the vicinity of Butte. Placer production from the Butte district, however, has been over-shadowed by the total output of byproduct gold recovered from the mining of lode deposits of copper, lead, and zinc.
Idaho Placer Deposits
Idaho was once a leading placer-mining State. One of the chief dredging areas is in the Boise Basin, a few miles northeast of Boise, in the west-central part of the State. Other placer deposits are located along the Salmon River and on the Clearwater River and its tributaries, particularly at Elk City, Pierce, and Orofino. Extremely fine-grained (or 'flour') gold occurs in sand deposits along the Snake River in southern Idaho.
Colorado Placer Deposits
Placers in Colorado have been mined in the Fairplay district in Park County, and in the Breckenridge district in Summit County. In both areas large dredges were used during the peak activity in the 1930's.
Oregon Placer Deposits
The most important mining regions of Oregon are in the northeastern part of the State where both lode and placer gold have been found. Placer gold occurs in many streams that drain the Blue and Wallowa Mountains. One of the most productive placer districts in this area is in the vicinity of Sumpter, on the upper Powder River. The Burnt River and its tributaries have yielded gold. Farther to the west, placer mining (particularly dredging) has been carried on for many years in the John Day River valley. In southwestern Oregon, tributaries of the Rogue River and neighboring streams in the Klamath Mountains have been sources of placer gold. Among the main producing districts in this region are the Greenback district in Josephine County and the Applegate district in Jackson County.
South Dakota and Washington
Minor amounts of placer gold have been produced in South Dakota (the Black Hills region, particularly in the Deadwood area, and on French Creek, near Custer) and in Washington (on the Columbia and Snake Rivers and their tributaries).
Nevada, Arizona, New Mexico
In addition to these localities, placer gold occurs along many of the intermittent and ephemeral streams of arid regions in Nevada, Arizona, New Mexico, and southern California. In many of these places a large reserve of low-grade placer gold may exist, but the lack of a permanent water supply for conventional placer mining operations requires the use of expensive dry or semidry concentrating methods to recover the gold.
Eastern US Placer Deposits
In the eastern States, limited amounts of gold have been washed from some streams draining the eastern slope of the southern Appalachian region in Maryland, Virginia, North Carolina, South Carolina, Georgia, and Alabama. Many saprolite (disintegrated somewhat decomposed rock that lies in its original place) deposits in this general region also have been mined by placer methods. Small quantities of gold have been mined by placer methods in some New England States. Additional placer deposits may be discovered in the East, but prospecting will require substantial expenditures of time and money. The deposits probably will be low grade, difficult to recognize, and costly to explore and sample. Moreover, most of the land in the East is privately owned, and prospecting can be done only with the prior permission and agreement of the land owner.
Gold Books and Panning Supplies
Looking for gold? We have over 50 different gold books and gold maps that show where gold has been found in the past and provide instruction on gold prospecting methods. Also available are gold pans in a variety of sizes and gold panning kits which include everything that you will need.
Lode Gold
Lode gold occurs within the solid rock in which it was deposited. Areas likely to contain valuable lode deposits of gold have been explored so thoroughly that the inexperienced prospector without ample capital has little chance of discovering a new lode worth developing. Most future discoveries of workable lode gold ore probably will result from continued investigations in areas known to be productive in the past. The districts in which such new discoveries of gold may be possible are too numerous to be listed in detail in this pamphlet. Some of the famous districts are: in California, the Alleghany, Sierra City, Grass Valley, and Nevada City districts, and the Mother Lode belt; in Colorado, the Cripple Creek, Telluride, Silverton, and Ouray districts; in Nevada, the Goldfield, Tonopah, and Comstock districts; in South Dakota, the Lead district in the Black Hills; and in Alaska, the Juneau and Fairbanks districts. Deposits in these districts generally are gold-quartz lodes.
| Sources of Gold Information |
| There are many publications of interest to those seeking more information about gold. The United States Geological Survey has published lots of reports about general geology and mineral resources for most of the major gold-producing areas. In addition most state geological surveys where gold production has occurred have compiled reports and maps to document the general geology, deposits and mining activity. There are also lots of prospecting guides and maps geared to amateur prospectors. |
Gold Deposits In Africa
Lode Gold Areas Have Been Thoroughly Prospected
Prospecting for lode deposits of gold is not the relatively simple task it once was because most outcrops or exposures of mineralized rock have been examined and sampled. Today's prospector must examine not only these exposures, but also broken rock on mine dumps and exposures of mineralized rock in accessible mine workings.
Undiscovered Gold is Finely Disseminated
Gold, if present, may not be visible in the rock, and detection will depend on the results of laboratory analyses. Usually, samples of 3 to 5 pounds of representative mineralized rock will be sent to a commercial analytical laboratory or assay office for assay. Obviously, knowledge about the geological nature of gold deposits and particularly of the rocks and deposits in the area of interest will aid the prospector.
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