January 06, 2020

In the precious metals bullion market, many metals can be bought, traded, and sold, including gold, silver, and copper. But how are these metals even foraged from the ground and mined to be the gorgeous beauts we see today adorning jewellery, art, collectibles, coins and many more?

Let’s break it down metal by metal:

Gold

First, what exactly constitutes gold? The gold atoms bond to one another via metallic bonding, which accounts for many of the properties of gold. How this bonding works is often dubbed “the sea of electrons.” Gold’s positively charged ions bond together in a crystalline structure while allowing other electrons to become “delocalized” in a way, since they are freed from their specific atoms and “swimming” in a sea of other electrons. 

The molecular structure is bound together because the electrons are attracted to many surrounding nuclei, which is thought to give off gold’s malleability. And that density and mobility of the electron sea also gives off the metal’s special lustre when light bounces off a gold item.

Gold is often taken from the earth via two forms of mining: placer mining, sometimes referred to as panning, and lode mining. Placer mining lets you extract gold from sediment such as sand and gravel. If you’ve ever seen a movie or show depicting the Old West, you’ve probably seen someone panning for gold by a riverbed, pan in hand, swirling water around its rim with a mixture of sediment that has been tossed in. As the lighter materials is washed out of the pan, heavier materials such as gold remain on the bottom, allowing the miner to reap the riches from his manual labor.

Lode mining works differently than panning: Instead of sifting through sand and earth in the hope of striking gold, those performing load mining extract gold from rock beneath the crust. This is another process usually portrayed in more large-scale mining operations in media. You’ve likely seen a long tunnel being dug into the side of a mountain or down into the earth, where miners are slowly breaking up earth in search of gold fragments. 


Although found in a near state of purity, the precious metal will sometimes be enriched with other metals to make it more durable, such as in Gold Mexican Pesos, which are made with 10 percent of copper to enhance their strength and durability so they can stand up to consistent circulation.

It’s important to know about the process of cyanidation, because more gold is recovered by cyanidation than by any other process. In cyanidation, metallic gold is oxidized and dissolved in an alkaline cyanide solution, and the oxidant employed is atmospheric oxygen, which, in the presence of a solution of sodium cyanide, causes the dissolution of gold and the formation of sodium cyanoaurite and sodium hydroxide, as Encyclopedia Brittanica explains.

When gold dissolution is complete, the gold-bearing solution is separated from the solids.

The post goes on to say: “With ores of higher gold content (i.e., greater than 20 grams of gold per ton of ore), cyanidation is accomplished by vat leaching, which involves holding a slurry of ore and solvent for several hours in large tanks equipped with agitators. For extracting gold from low-grade ores, heap leaching is practiced. The huge heaps described above are sprayed with a dilute solution of sodium cyanide, and this percolates down through the piled ore, dissolving the gold.”

Also, it should be noted that large-scale mining can be highly mechanized, formalized and regulated with many systems in place for maximizing production and decreasing risks. Small-scale mining can be more physically demanding, and unregulated, which means it often lacks state/industry support. Small-scale mining is identified as run by small groups of people who often live in poverty. These miners often don’t have the resources to implement systems for maximizing yields, for protecting their health and safety, or for environmental protection.

Silver

Silver mining uses similar methods to gold mining. But to source silver, there are two other methods used: by-product mining and ore processing. By-product mining isn’t much different than hard-rock mining, but the main purpose of this technique is to extract materials such as copper and sand. It just so happens that small quantities of silver may also end up being taken during the process. 

Ore processing is a bit different, and less often employed due to it being an expensive method. By harnessing cyanide, workers are able to weaken hard rock beds, which will then be crushed with machinery.

While some silver can be sourced from this process, it is not a reliable method, as the yields tend to be disappointingly low; also, it is extremely harmful to the environment, encouraging many ethical companies to avoid this method.

 Once the precious metal has been sourced, silver then moves on to the production stage, which often involves a process of electrolysis or chlorination to purify the metal. Similar to gold, silver will often feature other metallic elements added to it to increase the durability of the product produced, which is especially true for monetary coins used in national circulation and everyday jewellery.  

Copper

Most miners tend to find copper alongside other metallic deposits, including gold and silver, as well as other metals like lead and zinc. But, prior to the invention of modern copper mining processes, copper was only a byproduct sourced alongside these other metals, often giving off a small quantity at a time. 

If not sourced as a byproduct by the mining of another precious metal, copper is usually mined by drilling directly into a layer of sediment called a porphyry deposit. Once mined, copper might be utilized in its pure form for technological purposes, but it is often combined with other metallic components to produce a useful alloy.  

You may have gold and silver jewellery or collectibles that could give you a decent return. If you’re looking to sell and would like a free appraisal by Muzeum’s precious-metals experts, contact us anytime.


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