Properties of goldMost metallic artefacts recovered by archaeologists are fashioned from either gold or silver, which are thought to be the first metals to be worked by humans. They are both relatively easy to reclaim from the rocks in which they’re found, and are easy to work. Gold is extremely unreactive and doesn’t tarnish like most other metals. Consequently, gold jewellery can survive essentially unchanged for thousands of years.Gold is also extremely heavy, with a density of 19.4 g cm-3. The density of lead, by comparison, is only 11.4 g cm-3. Its heaviness plays a crucial part in many of the physical methods used to extract gold from its various sources.Gold is the most malleable (something is malleable when it is easily beaten into a thin film) element there is. Just 1g of gold (the size of a grain of rice) can be beaten into a thin film covering 1 square metre.Gold is also extremely ductile (something is ductile when it is capable of being drawn out as a wire under tension without breaking.)Pure gold is also a very soft metal. It will scratch easily, and it’s therefore unsuitable in its pure state for use as coinage or jewellery. For these purposes it’s usually alloyed with other metals such as silver, copper and zinc.