Science And Engineering Of Minerals - Gold, and many thought it to be tear drops from the sun.

Was actually taking a walk with a friend when we came about a precious stone, was glittering with its variants of colors making me wonder how such combinations came to be, it so much looked like something worth the value which got my friend overjoyed of the feeling that he might just be rich overnight, I did share in his fantasy too, you should know that feeling, to cut the long story short, we got to discover that it was just a minor rock of no value, but the view on my table was worth it though.

Today I decided to do something on a natural gift of value, not a rock but actually a metal of honor, one so sort by all and make many be like, "I got a pure gold chain and you can't beat that", GOLD

Wiki Commons: Gold Quartz by Rob Lavinsky of iRocks.com Free image licenced under CC BY-SA 3.0

Amongst numerous minerals we were blessed with by nature is gold, a mineral value and rear occurrence hence have been given a high standard even to being used as a means of exchange, there is so much to learn about gold starting from how they are formed down to being used by man and today we have gold in the spotlight.

Blogging today with Logic you will get to learn a bit about one of our nature's given precious metals, a metal which is not only the most ductile and malleable metal known to man but also a good conductor of electric charges.

In nature, gold is made of impurities which might include silver and other metals, a measure of how pure a gold is with reference to its karat (k), 24k denotes a pure gold without impurities, let's get to learn about this precious metal starting with its unique colour.

The Gold Colour

Unlike other metals gold is known for its unique reddish yellow colouration, gold is also known to vary in colour due to its level of purity and the metal in the combination, the colour rose gold is seen for an 18k gold which has copper as the additional metal, to get a white gold colouration, gold is alloyed with nickel or palladium, a 14k or 18k gold which has only silver as the contained impurity will be seen to a gold green colour ( a term for greenish-yellow couloration).

When gold is alloyed with iron, then a blue gold colour will be seen but when with aluminum, a purple gold colour is noticed, hence gold can be seen at different colours solely dependent on the alloying element and the level contained in the gold

Do you want to know the road taken by this mineral to become so precious?, what better place to get started than how it is formed in nature.

Formation Of Gold

You might have heard of gold rushes which gets everyone all scrambling for the slightest piece of gold the could lay their hands on, this actually happen on earth not like a place outside and you might just have the inclination that gold might just have been formed in these deposit over the years, I would burst the bubble saying that these gold discovered was not actually formed on earth.

If not formed in the Earth, Where then?

Gold was once described as the sweat which came from the sun by the Aztec people, this was probably due to the similarities in colour but when the question of the natural formation of gold and other metals were asked, a theory was brought explaining that gold might have been formed by a star going supernova, let's see how.

The early stage of the life of a star, it is made of hydrogen alone, as this undergo immerse heat and gravity, the atoms of hydrogen are seen to combine to form helium atoms, this condition continues seeing the helium atom fusing forming other large elements up until it reaches the formation of iron, then the end is said to be near for our star.

The fusion of a star can not go further than iron which is due to the amount of energy needed for the fusion of iron, as it is greater than the gravitational force which is being created by this star, this inability to fuse will see the build-up of iron just like a cancerous cell growth which will continue to a point up to a point when the star goes supernova, this explosion brings huge energy which is needed in the formation of heavy metals of which amongst them is the metal gold.

Theory 2 - The Collision Of Two Stars

This is another theory of the formation of gold which is believed by most just like the first, it was said that the formation of gold might have been from the collision of two neutron stars which bring a release of a very high amount of energy needed to form gold.

A neutron star is one which is burnt out hence only the center of the star is left remaining, they are known to burn slowly and produce less light compared to other stars. When two neutron stars are seen to orbit around each other space-time around the area will be wrapped by their density and they will eventually collide at last leading to the release of high amount of energy which is capable of forming heavy elements of which gold is Included.

These explosions by stars are said to form asteroids which travel to the earth and according to analysis, there is more gold deposit at the core of the earth than ever at the surface, these processes were said to have occurred billions of years ago and the gold sunk down to the core of magma in our planet and they are deposited there alongside other metals.

Discoveries Of Gold And The Mine

And the rushes came which saw so many countries benefit from this nature's gift, you don't have to blame the star for not falling just in front of your home, although sometimes I wished it had, but it fell where it fell and that saw South Africa being the major gold supply for the world since 1880s up until they were beaten to production by China in 2007, as of 1970 they were known to have supplied 79% of the total supply of gold supplying about 1480 tonnes of gold, today they are known to be the supplier of 50% of the total gold accounted.

Other countries known for the supply of gold are China, Canada, Peru, Australia, the United States, Ghana, Mali, Burkina Faso, Uzbekistan, Indonesia, and Russia.

Johannesburg, a city located In South Africa has its history to be from the Witwatersrand gold rush which saw to the highest recorded gold deposition in History. This deposition was in the north and Northwest end of Witwatersrand Basin. The mining of this discovered gold went to a depth of about 4000 meters which is the deepest mine in the world.

The 19th century saw so many gold rushes and a huge amount of gold was discovered in this period, the first gold discovery for the United States occurred close to Georgeville in 1803 at Reed Gold Mine, but the major gold rush was at a Georgia town, Dahlonega.

After Mining, The Extraction From Ore Follows

Sometimes the discovery of gold sees it alone but other times they may come in alloys of silver or mercury as the case may be but they be found in ores which includes krennerite, sylvanite, calaverite, nagyagite, and petzite (don't mind how cracking they might sound to the ears, they are real wealth though :) )

These ores can sometimes be found in underground mines or in open pits containing 5% gold or more in them, hence gold will need to be separated from its ore, first of all the ore is washed and filtered then they are sent to the mill where they are grounded which is followed by the extraction process.

The Cyanide Process Of Extraction

This is the most common way of separating gold from its ore and it can be done in various ways, one of the Cyanide processes of extraction involves putting the ore in a tank which contains weak solution of Cyanide and zinc added to it this result to a chemical reaction separating the gold from its ore then a filter press is used to collect the gold from this solution.

Another Cyanide process known is the carbon-in-pulp process of separation, in this process, there is mixture of the ground ore with water and the Cyanide is then added followed by the addition of carbon which creates a bond with gold and the particles from carbon and gold combination is inserted in a solution of caustic carbon where the gold is now separated from carbon.

The Third Cyanide process is the heap-leaching process which sees the ore being sprayed with Cyanide after placing them on an open-air pad, the gold contained in the ore is then leached downward through the pad into a place where it is recovered, this might take quite a long time but this process is often used when it might be expensive to extract an amount of gold from its ore.

Aside from the Cyanide process of extraction, another known process of extraction is the amalgamation process which involves passing ores through plates which is coated with mercury and hence when the gold comes in contact with the Mercury, they form a mixture also known as an amalgamate of mercury and gold. Gold can thus be collected by boiling out mercury gas as it has a lower boiling point that gold hence the gold is left to be collected.

When this gold is collected, they are in their impure state, further treatment is needed to bring them to their required pure form , this takes us to the refining process of our mineral.

Refining For A Pure State

After the mining of gold, they tend to contain impurities which might include metals like iron, zinc, copper, and silver, these impurities make the gold to be in an impure state and to be used or regarded as a gold of value, these impurities must be removed. Several methods have been proposed from history to remove these impurities from gold but the of the two methods are currently in practice in the purification of gold are the Miller process and the Wolhwill Process.

The Miller Process

The Miller process of purification of gold is based on the fact that the impurities contained in gold when mined have one thing in common, they can all combine with chlorine gas to form chlorides which can be separated from gold known to be less affected by chlorine, this process can be used to get gold which is 99.95% pure, this can do though .

Miller process involves heating the gold to a molten state and passing chlorine gas across its melting crucible containing the molten gold, the chlorine mix with impurities contained in the gold form a slag of chloride which will float on the molten gold and the slag is then skimmed off to separate the molten gas from the gold.

The heating process is done with an induction furnace and the chlorine gas is then brought into the picture by a rotating lance which is controlled, this removes by metals such as nickel, silver copper and any metal which may be present in the combination. It also goes as far as removing some atmospheric elements such as bismuth, sulphur, tellurium, and arsenic by forming a chloride slag of them all.

The slag formed is removed by pouring into a crucible which is allowed to cool slowly and the gold which was poured alongside the slag is then removed as they will settle at the bottom of the mixture, when cooled they can easily be removed by picking with the hand or a separating mold used as they are in forms of buttons of gold. The miller refining process takes about 2-4 hours and when concluded, the gold gotten can be further purified through the Wolhwill purification process as metals like copper and silver may still remain in the gold making it less pure but the gold gotten in this process is good enough for commercial use.

The Wolhwill Process

This is a known process which can be used to get gold 99.999% pure, it was introduced by a German engineer by name Hanson Emil Wolhwill in the year 1874, the Wolhwill Process is a more expensive and complex process than the Miller process but if done right can produce very pure gold samples

In this process of gold processing, three important components are prerequisite for the process, they are an anode(this is the positive terminal of an electrolytic cell), the cathode ( the negative terminal of an electrolytic cell) and an electrolyte which is a substance which the others are inserted to form the electrolytic cell.

The cathode used in this process is made of 24k gold(a very pure gold) pressed into gold sheet, the anode made of impure gold which is about 95% pure or more or less as the percentage of impurity determine the overall efficiency of the purification process. The electrolyte is an acid called the chloroauric acid which can be gotten from desolving gold in aqua regia (a powerful acid).

After setting up this electrolytic cell, current is passed through the cell from the anode which conducts electricity and it travels into the electrolyte and then to the cathode and as this process goes on, the anode which is made of impure gold dissolves and is deposited in the cathode of 24k gold up till it is completely dissolved and deposited, hence a very pure gold is formed in the cathode which can be melted to any required shape.

As you might have noticed, every part of the electrolytic cell is made of gold hence making this process a costly one as more gold is needed to make pure gold most especially converting to a chloroauric acid hence making the Wolhwill Process costly than the Miller process therefore, the Miller process alone is often used for gold purification as it has a quick turnaround time and can produce pure gold at large amount and less cost.

Now we have our gold, 99.999% pure, highly reverend, ready for use, i have compiled a list of some common uses of gold by man, lets have a peak on the uses of gold.

Common Uses Of Gold By Man

The use of gold has spanned through a wide range of humanity, it's use is dated back to the early culture of people when gold was seen and admired by man.

Gold is a malleable metal which can be rolled into wire and just like copper and other good metals, they are good conductors of electricity and do not undergo any form of tarnishing when exposed to certain harsh conditions and just like you well know it's highly regarded for its unique shiny colour.

All these make the use of gold to span through so many aspects of man and I will be highlighting some important but common use of gold in humanity.

They are Good For Making Quality Jewelry

In our world today, one of the most common uses of gold is in the ornament industry, due to its high value and admirable properties, the use of gold as ornaments have been seen to consume approximately 78% of the total use of gold. This use of gold has been dated back to early cultures as gold was considered a durable and beautiful metal.

Gold has been a metal for the rich due to its high regards hence it is highly regarded when worn as crowns, `chains, bangle, necklaces or adorned in parts of clothing, a part of the world known for adorning the body with gold in India as its a way to show wealth.

Gold As Medals and Awards

One of the major things we know the gold for is its standard in awards and medals as we have placed them, gold is quite a precious metal to behold and this has seen it held high being used as awards, crowns and religious objects these have seen gold to be used as first place Olympic medals, academic prizes and lots more.

Gold is pleasing to behold, highly valued thus it has been seen to fit this application very well.

Gold In The Aerospace Industry

The use of gold have also spanned through the aerospace industry as it have seen various use in the construction of aircraft with emerging technologies, thay have been known to be used both in electric parts for conducting electricity, mechanical parts and also as a means to protect those in a plane by coating the inner layer of the aeroplane with gold as it is known to shield from infrared radiation.

Gold In Electronics and Computers

Gold is a metal and just like some other metals, they are very good conductors of electricity being able to transmit electric charges from one end to another and because of this property, the use of gold has also been seen in the electrical industry being used in some electronic devices just like television, cell phones GPS and some other electronic applications.

Due to their very good ability to conduct electricity, they have also been used in laptops and desktops in the transfer of information from one part to another but due to the high cost of this metal, gold has not seen very commercial use in the market in this regard like other metals like copper which can be gotten at a lower cost.

For Finance And Investment

Gold has been known to be a metal of high value and due to its rear occurrence in nature, it has been seen to be used as a Natural currency of high value. Before now the gold standard has been used to hold the monetary value of the currency of the United States and the value of gold in this Millennium have been seen to rise in the world's stock market.

When investing in gold, the investment can be done in form of gold bars, gold coins, and gold bullion and this can be seen to be a way to survive an unstable economic monetary value of a particular currency hence the value of gold as finance or investment will still be one of man's major use of gold being accepted as a means of value and exchange.

Gold In Medical Field

Gold has also seen applications in medicine and dentistry as they have been known to be a metal which is inert in nature, easy to insert amongst other properties, they have span through being used as crowns, fillings and orthodontic appliance. Gold has also been known to be used in radiation in some diagnosis and radiation treatment.

The use of gold in dentistry have been known to be dated back to around 700BC as many have seen it to be a good option for the replacement of either a missing or broken teeth.

Bringing It All Together

This is an amazing object an being a gift from nature make it more awesome, an object of value, many say it's a solidified teardrop from the sun, it looks more like it though. Gold is a precious metal with an amazing unique colour and being limited supply gives it the worth, you can say nature just planned a good proportion of supply.

Over the years many have tried to synthesise gold from other metals of which lead was thought to be the best metal for this, according to Wikipedia, success was not recorded until the first gold was synthesized from mercury by Hantaro Nagaoka in 1924, this followed another synthesis in 1941 by a group of Americans and today it is now known that gold can be manufactured using a nuclear reactor from mercury and platinum, a process termed irradiation and this is quite an achievement by man.

Would you have believed?, there exist a bacteria which poop tiny pure gold nugget as side effect taking in toxic metal, they are Cupriavidus metallidurans(renamed Ralstonia metalliduransacross), came across them and I was like, OH I wish I can poop some gold even just for a day. Learn more about this bacteria here

Source Articles

Uses Of Gold

Gold Wikipedia

Extraction From Ore

The Wolhwill Process

The Miller Process

Formation

Gold Mineral

I hope you enjoyed learning about gold and the road it had to pass to be such a wonderful object used by man, I also did learn a lot too putting this piece together and I hope you join me next time on a better version learning about minerals, Stay Cool.