Gold is the most malleable of all metals, making it easily worked, and just one gram of gold can be hammered into a one square metre sheet. Gold is also extremely heavy, which makes it easy to collect. Much gold is found in alluvial sources, and because it is heavier than any other particles in the river, it can be separated from other minerals and debris. It is said that the ancients used sheep fleeces to filter rivers with gold deposits, into which the heavy gold pieces would become embedded perhaps resulting in the Ancient Greek myth of the Golden Fleece.
Unlike most other metals, gold is also non-corrosive, not to mention exceptionally beautiful, and thus it is no surprise that it has been coveted since ancient times. The oldest known gold articles were found in Bulgaria, however the ancient Egyptians are perhaps best known for the finest ancient gold jewellery. The Egyptians sourced their gold from Nubia, an area in the southernmost part of modern day Egypt. Nubian gold was made into some of the most famous ancient gold artefacts known today, including the treasure of King Tutankhamen.
Gold is never found in its pure form, but instead mixed with other metals (known as an alloy) most often silver and copper. Pure gold, from which all impurities have been removed, is known as 24 carat gold. The measure of fineness of gold expressed as a percentage of pure gold to other added metals, this being the benchmark for purity. 18 carat gold, for example, is eighteen parts pure gold and six parts other alloy metals.
The colour of gold, which is naturally yellow, can be altered depending on the type and amounts of alloy metals added. In addition to yellow, other colours of gold are white gold, green gold, and red (or rose) gold. The further benefit of such alloys is that they increase the hardness of gold, which is naturally quite soft, making it more durable and, in turn, more suitable for jewellery.
Gold work is often marked with a hallmark or small stamp which indicates its purity, often in addition to the stamp indicating the maker, or maker's mark.