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GOLD




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GOLD FACTS

Gold is so heavy that one cubic foot of it weighs half a ton.

All of the gold in the world could be compressed into an 18-yard cube that would weigh about 3,000 tons.

A one-ounce gold nugget is more rare than a five-carat diamond.

Gold is the heaviest metal known - six to seven times heavier than its nearest competitor.

Gold can be hammered so thin that sunlight can shine through it; 200,000 sheets would be only 1" high.

A single ounce of gold can be drawn into a wire 60 miles long.

There are 25 tons of gold in every cubic mile of sea water - about 10 billion tons of gold in the oceans.

Gold is so soft it is seldom used in its pure (24K) form.

Jewelry that is marked 10K is made of 10 parts gold, and 14 parts other metals.

The Moh's hardness of pure gold is 2-1/2 to 3; melting point is 2,063 degrees F; specific gravity is 19.32.

In 1933, the U.S. government banned private ownership of gold. The ban was lifted on December 31, 1974.

Gold is measured in Troy ounces (see the bottom of this page for conversions).




PLACER GOLD

DEFINITION: A placer deposit is a concentration of a natural material that has accumulated in unconsolidated (loose) sediments of a stream bed, beach or residual deposit. Gold freed by weathering or other processes from lode deposits is likely to accumulate in placer deposits because of its weight (gravity causes it to migrate toward the lowest spot) and resistance to corrosion. In addition, its characteristically sun-yellow color makes it easily and quickly recognizable even in very small quantities.

Placer gold mining in the United States spans a period of nearly 200 years. Earliest mining took place in the Eastern States and particularly in the southern Appalachian region during the late 1700's and early 1800's, but the richer deposits were soon exhausted, and interest turned to the West. The earliest production of any note in the West was from the Old and New Placer Diggings near Golden, Santa Fe County, N. Mex. These deposits were worked as early as 1828.

A few other deposits were mined in the succeeding years until the discovery by James Marshall on January 24, 1848, of gold in the gravels of the American River at Coloma, Calif. This discovery was a major factor in the rapid settlement of the West and triggered the SECOND of the great gold rushes in the United States. The FIRST was, of course, Conrad Reed's find on Little Meadow Creek in 1799. Because of the lure and excitement of gold mining, prospectors spread throughout the West and in subsequent years many more rich placer gold deposits were found.



LODE GOLD

DEFINITION:Lode - or "vein" - gold occurs within the solid rock in which it was deposited. If the particles of lode gold are very small - as is often the case - they may not be visible to the naked eye. In such cases, detection will depend on the results of laboratory analyses.



GOLD MINING METHODS

Among the early methods developed for recovering gold were the gold pan, the rocker, the dip-box, the long tom and the sluice. The pan is generally too slow to be effective for anything more than prospecting. The rocker is a time-honored tool of the small-scale miner with limited means. The dip-box and long tom might be considered more like simplified sluicing methods than distinct methods. The long tom method was never very popular. The simpler methods all normally involve hand-mining operations (shoveling and/or picking of the gold-bearing materials).



PANNING FOR GOLD

gold panning

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, most commonly used and least expensive method for a prospector to separate gold from the silt, sand and gravel of stream deposits.

Prior to the 1950's, gold pans were made primarily of stiff sheet iron. Today, most pans are made of plastic. The original standard pan was 16 inches in diameter at the top and 2-1/2 inches deep. The rim flared outward at an angle of about 50 degrees from the vertical. Smaller pans were used for testing. A 10-12 inch size pan is usually best for ease of handling and the 12-inch is the most widely available. Frying pans or other cooking utensils may also be used for panning gold but are less effective.

There are different techniques and subtle variations in the art of panning - experience teaches which is best. Those with wide experience and much practice can recover the most gold with the least effort.

The pan is usually filled level with the top, or slightly rounded, depending somewhat upon the nature of the material being washed and the personal preference of the panner. It is then submerged in water. Still water 6 inches to 1 foot deep is best. While under water the contents of the pan are kneaded with both hands until all clay is dispersed and the lumps of dirt are thoroughly broken. Stones and pebbles are picked out after the finer material (referred to as "fines") are washed off. The pan is then held flat and shaken under water to permit the gold (which will be much heavier than any other material in the pan) to settle to the bottom. The pan is then tilted and raised quickly - keeping it under water. Such action will result in a swirling motion in the water causing the lighter material at the top of the pan to washed off. This operation is repeated until all the lighter material is gone from the pan leaving only the gold and heavy minerals behind.

Nuggets and coarse pieces of gold (called "colors") can now be picked out readily with a tweezer. Cleaning the black sand from the finer gold is more difficult and requires careful attention to prevent the finer colors from washing out of the pan during the process. This part of the operation is usually done over in a tub or over another pan so that if any gold is lost it can be recovered by repanning.

The "concentrates" (the remaining material) should be dried, and the black sands (composed largely of magnetite) can then be removed by using a magnet or by spreading the concentrate on a flat surface and gently blowing across it.

A word should be said here about other minerals that you may see in your gold pan. Pyrite ("fool's gold," an iron sulfide) and mica are often mistaken for gold by the novice. Pyrite, which is usually a brassy yellow to white color, will shatter when struck with a hammer and becomes a black powder when finely ground. Mica, which may have a bright, bronzy appearance, is distinguished by its light weight and flat, platy cleavage. Both minerals are common in gold areas.

Other minerals that will collect with the gold and black sands because of high specific gravity include ilmenite (iron-titanium oxide), hematite (nonmagnetic iron oxide), marcasite (an iron sulfide), rutile (titanium oxide), scheelite (calcium tungstate), wolframite (iron, manganese tungstate), tourmaline (boron and aluminum silicate), zircon (zirconium silicate), chromite (iron and chromium oxides), and cinnabar (mercury sulfide). If present in sufficient quantity, these latter minerals may have some economic significance, although efforts to recover them as by-products are seldom worthwhile.



USING A ROCKER

gold rocker

At least twice as much gravel can be worked per day with a rocker as with a pan. The rocker or cradle, as it is sometimes called (since it resembles one), must be worked carefully to prevent loss of fine gold. With the rocker, the job of washing is less strenuous but the method used in extracting the gold is virtually the same as panning.

The rocker, like the pan, is used extensively in small-scale placer work, in sampling, and for washing sluice concentrates and material cleaned by hand from bedrock in other placer operations. One to three cubic yards can be dug and washed in a rocker per man-shift, depending upon the distance the gravel or water has to be carried, the character of the gravel and the size of the rocker. Rockers are usually homemade and display a variety of designs. A favorite design consists essentially of a combination washing box and screen, a canvas or carpet apron under the screen, a short sluice with two or more riffles, and rockers under the sluice. The bottom of the washing box consists of sheet metal with holes about 1/2 inch in diameter punched in it, or a l/2-inch-mesh screen can be used.

After being dampened, the gravel is placed in the box, one or two shovelfuls at a time. Water is then poured on the gravel while the rocker is "rocked" back and forth. A small stream from a pipe or hose may be used or water can be poured from a bucket. The gravel is washed clean in the box, and the oversize material is inspected for nuggets, then dumped out. The undersize material goes over the apron, where most of the gold is caught. Care should be taken that not too much water is poured on at one time, as some of the gold may be flushed out. The riffles stop any gold that gets over the apron. In regular mining work, the rocker is cleaned up (material caught behind the riffles is removed) after every 2 to 3 hours or perhaps more often when rich ground is worked and gold begins to show on the apron or in the riffles.



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