GOLD - What is it exactly?

 

    Gold is a chemical element, represented by the symbol Au (derived from the Latin, aurum, meaning gold).


    A chemical element is defined as a pure chemical substance consisting of one type of atom distinguished by its atomic number (number of protons in its nucleus). For example, oxygen (O) is a chemical element made entirely from oxygen atoms, whereas water is a chemical substance made of hydrogen (H) atoms combined with oxygen (O) atoms to give water (H2O) molecules. The chemical element gold (Au) has an atomic number of 79.


    When chemical elements are found in nature they are found with impurities, which is why gold (Au) ores, silver (Ag) ores, or iron (Fe) ores for example need to be processed to isolate the desired element. Gold nuggets also form with some impurity, however one of the unique characteristics of gold found in nature is just how pure it can be compared to other metals found in nature. Gold nuggets typically run at over 90% pure gold, particularly Australian ones, with the remaining 10% or less often comprising of silver, palladium or copper. This naturally occurring purity, combined with some other of gold’s unique characteristics - its startling density, its extreme malleability, its durability, and its beautiful natural lustre which doesn’t tarnish - is what first brought gold to the attention of ancient peoples and what drove gold to its esteemed standing in society.


    When I say startling density, I mean just that. Invariably when someone holds a nugget for the first time their surprised reaction is, “Wow, that’s heavy”. Even though lead has a higher atomic number than gold (82 protons in the nucleus of a lead atom compared to 79 protons in the nucleus of a gold atom), gold is much heavier than lead due to its extraordinary density: one cubic centimetre of gold weighs 19.3 grams compared to one cubic centimetre of lead weighing 11.34 grams, thereby making gold almost twice as heavy as lead. This is caused by the crystal structure that gold forms in the solid state: the tighter bonds of gold atoms bring them to a distance of 2.88 angstroms from each other compared to 3.5 angstroms between lead atoms, hence the increased density. The result is quite surprising, making holding a gold nugget an experience on that score alone.


    The extreme malleability of gold, on the other hand, is something not as often experienced, as taking a hammer to a precious gold nugget or gold bar is not something one is likely to do! Though if you did, you could, with a little practise, hammer out one gram of gold into an incredible one square metre of very thin gold foil (otherwise known as gold leaf). One sheet of gold leaf can be as thin as 0.000127 millimetres, or about 400 times thinner than a human hair. Once again this unusual characteristic is a result of the atomic structure that gold forms in the solid state, as is the related characteristic of being the most ductile of metals (able to be drawn out into a thin wire): one gram of gold can be drawn out into a wire over two and a half kilometres long! Both of these characteristics meant gold could be worked with relative ease from early times to create jewellery and other works of art.


    Likewise, gold’s natural shining lustre and resistance to tarnishing made it a desired material for personal adornment and art from the earliest of times (see the History section for more about just how early mankind became aquatinted with gold). These particular characteristics stem from gold’s stable and inert chemical nature - it doesn’t react with oxygen for instance and so doesn’t rust. With this in mind, one can see how the pursuit of gold developed. Despite its rarity, the fact that gold does exist in a pure and stable (and attractive) form in nature actually enabled the quest for it to exist. Though nowadays mining of lode gold (microscopic gold particles in soil or rock) accounts for the vast majority of the world’s gold production, the first finders of gold would undoubtedly have been those who found natural nuggets. It is estimated that only a few percent of today’s world gold production is in the form of nuggets, making those beautiful natural creations even more rare and valuable than the metal itself.


    What an amazing metal it is all considered. And no wonder it attracted our attention so early and has held us enthralled for so long. This enthralment - dare I say obsession - has motivated great deeds of adventure as well as treachery over the centuries, and our passion for gold has not ebbed with modern times: still it calls us in pursuit, whether on an industrial scale as with the active mining endeavours across the globe, or on an individual scale in the pursuit of personal wealth and security.