The Love Scout

The precious metal of gold has fascinated humans for thousands of years. But how do we actually get it out of the ground? Let’s take a look at the most common ways to mine gold.

There are two main gold mining methods, one is called “placer” and the other is “vein” mining. And another type of mining is when gold is collected as a by-product in the mining of other metals.

Placer Mining

Placer mining is practiced when the metal is found in unconsolidated deposits of sand and gravel from which the gold can be easily separated because of its high density. The sand and gravel suspended in moving water. Much heavier metal sinks to bottom and is separated by hand.

The simplest method of placer mining is panning. Here the miner swirls the mixture in a pan rapidly enough to carry the water and most of the gravel and sand over the edge while the gold remains on bottom. This was the classic method used by the Forty-Niners during the California gold rush of 1849 and has been immortalized in story, art, and song.

A more efficient form of placer mining uses a sluice box, a U-shaped trough with a gentle slope and transverse bars firmly attached to the trough bottom.

The bars — extending from side to side — catch the heaviest particles and prevent them from washing down the slope.

Sand and gravel are placed in the high end, the gate to a water supply is opened, and the lighter material is washed through the sluice box and out the lower end. The materials are caught behind the bars and are gleaned to recover gold.

Another variation of placer mining is called hydraulic mining. A very strong stream of water is directed at natural sand and gravel banks washing away the lighter materials. The suspended materials treated as if they were in giant sluice box.

Currently the most important placer technique is dredging. A huge shovel of several cubic meters capacity lifts the unconsolidated sand and gravel from soil and mud and the placer process starts.

Vein Mining

Vein, or lode mining is the most important of gold recovery methods. Each ounce of gold recovered requires the processing of about 100,000 ounces of ore. Much gold is deposited in rock veins and this method accounts for more than half world’s total gold production. Gold in veins may be of microscopic particle size, in nuggets or sheets, or in gold compounds. The ore requires extensive extraction and refining.

One-third of all gold is produced as a by-product of copper, lead, and zinc production. Copper must be electrolytically refined to raise its purity from 99% to the more than 99.99% that is required for many industrial purposes.

In the refining process an anode of impure copper is electrolyzed in a bath in which the cathode is a very thin sheet of highly refined copper. This process

creates anode sludge which contains gold in quantities sufficient to make its recovery profitable. One-third of all gold is obtained from such by-products.

Silver and platinum are also recovered from the copper anode sludge in quantities large enough to more than pay for the total refining process.

Extraction, Refining and Uses of Gold

Ore from the gold mine is first crushed in rod or ball mills. This process reduces the ore to a powdery substance. The gold is then extracted by amalgamation with mercury or by placer procedures. Approx. 70% is recovered at this point.

The remainder is then dissolved in dilute solutions of sodium cyanide or calcium cyanide. The addition of metallic zinc to these solutions causes metallic gold to precipitate. This precipitate is refined by smelting and the purification is completed by electrolysis. The sludge produced in this process will also contain commercial quantities of silver, platinum, osmium, and other rare-earth metals.

Gold is one of the first two or three metals, along with copper and silver that was used by humans in these metals’ elemental states. Because of its poor chemical reactivity it was found uncombined and required no knowledge of refining. Gold was used in decorative arts before 9000 BC. And civilizations prized gold for its beauty.

A principal use of gold today is as a currency reserve. For centuries gold was used directly as currency along with silver. During the 19th century, gold assumed the role as the sole basis of the currencies of most nations. Paper money was directly convertible into gold.

World War I, however, disrupted the “gold-standard” system. The original gold standard was gradually abandoned. The United States stopped minting gold coinage in 1934 and the dollar eventually emerged as the principal unit of international monetary transactions.

Since the 1970s, gold has been bought and sold on the world market, with widely fluctuating prices. Today gold reserves maintain only a very indirect relationship with currency values. However, as gold has declined as a currency reserve, its use in industrial processes has risen. On top of this, its beauty and workability continue to give gold an important role in the world’s jewelry industry.

gold dredges

In the modern world, African baskets are a hot commodity with collectors and designers. The term itself is misleading to say the least. “African” denotes an entire continent and thousands of different peoples and nationalities. To say that a basket is an authentic “African” product is like saying that a French basket is authentic “European.” The baskets of Africa are as varied and diverse as its people.

The people of the Zulu tribe who are located in South Africa have long utilized baskets for gathering as well as use in a number of religious ceremonies. The materials that are most commonly used for the basket itself are the Ilala Palm and Ncebe, which is the bark from the wild banana tree. The two are interwoven to make the basket more colorful, as the palm itself is naturally a plain cream color.

Certain berries, plants, roots, and other ingredients are used to create dyes for use in the Zulu basket. Brown and black are made from boiling tree roots for several days, while purple and blue are created by boiling Umdoni berries. Coral comes from the aloe plant, while orange comes from a small root of a plant being boiled. Maroon and burgundy is extracted from the bark of the Marula tree while pink and lilac are made from the leaves of a small bush. Yellow is extracted from a combination of wood ash and water while grey is made from plants that are soaked in mud for at least a week. Khaki green comes from even more unusual source-cow dung that is boiled with palm leaves.

Zulu basket makers also weave particular designs in the fibers of these containers that denote specific things. For example, a triangle pattern in a Zulu basket means “masculine” while a double triangle means “married man.” “Feminine” is symbolized by a diamond and a double diamond means “married woman.” A good luck and prosperity basket will have a design of squares or dots on it. Baskets are also woven especially for a bride on her wedding day. She will give this basket to her new husband to drink beer out of. A depiction of the marriage will be woven into the fibers to serve as a record of the event for future generations. Other historical designs that are popular on Zulu baskets include a series of diamonds which stands for “the shields of Shaka” and a zig-zag pattern that denotes “the assegais of Shaka.”

There are several different styles of Zulu baskets. As mentioned before, there is a beer basket that is specially designed to be watertight. There are also open baskets that are used for gathering food.

While many of these baskets are still used for particular occasions and religious ceremonies, the Zulu basket weavers have found a prosperous outlet for their talent in the sale of their products. European and American consumers are willing to pay extravagant prices for these authentic “African” baskets. In many cases, this income may be the only money that the family has, so the basket weavers are more than happy to peddle their wares while maintaining the same quality that the Zulu basket weavers have carried on through the generations.